Procedure examination chairs

Midmark 413: troubleshooting and error codes

The ServiceForge knowledge base holds 13 documented symptoms for the Midmark 413, with 34 ranked causes, 33 diagnostic checks with test points and expected values, and 1 error codes. Each symptom below shows its causes and the first check; the rest is one connection away. Connect ServiceForge to your AI

Symptoms

SEAT UP and SEAT DOWN functions do not work caution

When SEAT DOWN or SEAT UP footswitch is depressed, nothing happens.

Ranked causes

1. Wire connections loose (common)
2. Treatment pan assembly not fully stowed (occasional)
3. Pan safety limit switch malfunctioning (occasional)
4. Seat capacitor weak or blown (occasional)
5. Thermal overload switch activated (occasional)
6. Seat actuator assembly malfunctioning (occasional)

First check

Check wiring connections and voltage

Test point: SEAT DOWN footswitch to terminal block connections
Expected: proper voltage at connections VAC, +/- 5 VAC
Tools: multimeter

4 more checks with pass and fail actions, 6 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

BASE DOWN function does not work caution

When BASE DOWN footswitch is depressed, nothing happens.

Ranked causes

1. BASE DOWN footswitch malfunctioning (common)
2. BASE UP footswitch sticking open (occasional)
3. Base down limit switch tripped (common)
4. Base down limit switch malfunctioning (occasional)
5. Seat up limit switch malfunctioning (occasional)

First check

Perform continuity check on BASE DOWN footswitch

Test point: BASE DOWN footswitch COM. and N.O. terminals
Expected: continuity when activated
Tools: continuity tester or multimeter

4 more checks with pass and fail actions, 5 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

BASE UP and BASE DOWN functions do not work caution

When BASE UP or BASE DOWN footswitch is depressed, nothing happens.

Ranked causes

1. Wire connections loose (common)
2. Base capacitor weak or blown (occasional)
3. Thermal overload switch in base actuator motor activated (occasional)
4. Base actuator assembly malfunctioning (occasional)

First check

Check wiring connections and voltage

Test point: BASE UP footswitch to terminal block connections
Expected: proper voltage at connections VAC, +/- 5 VAC
Tools: multimeter

2 more checks with pass and fail actions, 4 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Chair will not operate caution

Foot control footswitch is depressed, actuator motor does not run or hum.

Ranked causes

1. Power cord not plugged in (common)
2. Facility circuit breaker tripped (common)
3. Fuses blown in AC connector (export models) (occasional)
4. Wire connections loose (occasional)

First check

Verify power cord connection

Test point: facility wall outlet
Expected: power cord plugged in

3 more checks with pass and fail actions, 4 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Chair moves slowly or not at all for heavy patient patient safety

Chair moves fine for light patient, but will not move or moves slowly for very heavy patient.

Ranked causes

1. Low voltage supplied to chair (common)
2. Table overloaded with too heavy patient (common)
3. Capacitor weak (occasional)

First check

Measure voltage at wall receptacle

Test point: wall receptacle where chair is plugged
Expected: 115 +/- 5 VAC (domestic) or 230 +/- 10 VAC (export), +/- 5 VAC
Tools: multimeter or voltmeter

2 more checks with pass and fail actions, 3 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

SEAT DOWN function does not work caution

When SEAT DOWN footswitch is depressed, nothing happens.

Ranked causes

1. SEAT DOWN footswitch is malfunctioning (common)
2. Seat down limit switch is tripped (common)
3. Seat down limit switch is malfunctioning (occasional)

First check

Perform continuity check on SEAT DOWN footswitch

Test point: SEAT DOWN footswitch COM. and N.O. terminals
Expected: continuity when footswitch activated
Tools: continuity tester or multimeter

2 more checks with pass and fail actions, 3 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

BASE UP function does not work caution

When BASE UP footswitch is depressed, nothing happens.

Ranked causes

1. BASE UP footswitch malfunctioning (common)
2. Gas spring malfunctioning (occasional)

First check

Perform continuity check on BASE UP footswitch

Test point: BASE UP footswitch COM. and N.O. terminals
Expected: continuity when activated
Tools: continuity tester or multimeter

1 more check with pass and fail actions, 2 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

SEAT UP function does not work caution

When SEAT UP footswitch is depressed, nothing happens.

Ranked causes

1. SEAT UP footswitch is malfunctioning (common)
2. SEAT DOWN footswitch stuck open (occasional)

First check

Perform continuity check on SEAT UP footswitch

Test point: SEAT UP footswitch COM. and N.O. terminals
Expected: continuity when footswitch activated
Tools: continuity tester or multimeter

1 more check with pass and fail actions, 2 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Foot extension locking mechanism malfunctioning caution

Foot extension does not lock into stowed position or extended position automatically.

Ranked causes

1. Foot extension lock/unlock mechanism malfunctioning (common)

First check

Inspect return spring and linking rod

Test point: foot extension lock/unlock mechanism
Expected: return spring and linking rod present and intact

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Pan safety limit switch misalignment patient safety

Pan safety limit switch trip arm does not trip at correct position, causing pan holder to lock before or after switch activation.

Ranked causes

1. Incorrect pan safety limit switch position (common)

First check

Observe switch trip timing during pan insertion

Test point: Pan holder assembly fully stowed position
Expected: Trip arm of switch trips just before pan holder locks into stowed position

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Seat actuator installation alignment patient safety

Seat actuator swivel joint not properly aligned, causing seat section to not be level with floor.

Ranked causes

1. Swivel joint screw adjustment needed (common)

First check

Test seat level after installation

Test point: Seat section relative to floor
Expected: Seat section level with floor and parallel spacing

2 corrective actions and part numbers are in ServiceForge. Connect ServiceForge to your AI

Seat up limit switch misalignment patient safety

Seat up limit switch trip arm not properly positioned in actuator shaft cutout, causing switch to trip at wrong time.

Ranked causes

1. Incorrect switch installation or adjustment (common)

First check

Verify trip arm position in cutout

Test point: Seat actuator shaft cutout
Expected: Trip arm of switch in cutout of seat actuator shaft

1 more check with pass and fail actions, 1 corrective action, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Whirling or squeaking noise from actuator caution

Whirling or squeaking noise is heard when an actuator assembly is being run.

Ranked causes

1. Foreign matter on ball screw or lack of lubricant (common)

First check

Inspect ball screw threads

Test point: actuator assembly ball screw threads
Expected: clean, no foreign matter, adequate lubricant

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Error codes

Code	Meaning	Trigger	Severity
`SEAT_NOT_LEVEL`	Seat section is not level with the floor after installation	Seat actuator assembly installed with swivel joint at incorrect angle	warning

Likely causes and actions for each code are in ServiceForge. Connect ServiceForge to your AI

Community

0 fixes logged by technicians through their AI, with outcomes, for this model.

ServiceForge knowledge base record. Field-unverified unless technicians confirmed it. A teaching summary of the record, not a service manual. Export 2026-10-14.