This illustration shows the base limit switches and the three serviceable components of the base actuator. Use the table below to isolate the malfunction.

Problem	Required Action
Motor runs, but makes grinding noise.	Clean / lube actuator threads. Replace actuator if necessary.
Motor runs, but table does not move.	Inspect / replace motor coupler.
Motor does not run.	Perform Limit Switch Test. If OK Perform Actuator Motor Test

Lube threads w/lithium grease.

1.Disconnect harness from J13 on main PC board.

2.Place one meter probe on the common - green.

3.Place other meter probe on the wire corresponding to the desired switch - see illustration.

With Switch Untripped
Meter Reading	Required Action
OL	Perform Limit Switch Continuity Test
less than 10 Ω	Limit switch / harness - OK Perform Actuator Motor Test

With Switch Tripped
Meter Reading	Required Action
less than 10 Ω	Perform Limit Switch Continuity Test
OL	Limit switch / harness - OK Perform Actuator Motor Test

1.Tag / disconnect wires from switch.

2.Place meter probes on COM and NC terminals.

With Switch Tripped
Meter Reading	Required Action
OL	Replace limit switch.
less than 5 Ω	Limit switch OK, Replace limit switch harness.

With Switch Untripped
Meter Reading	Required Action
less than 5 Ω	Replace limit switch.
OL	Limit switch OK, Replace limit switch harness.

1.Tag, then disconnect base actuator wires - J1 and J2.

2.Place meter probes on actuator wires. Check meter reading.

Meter Reading	Status	Required Action
1 to 10 Ω		Actuator motor OK. Perform Motor Ground Test
OL or less than 1 Ω		Replace motor*.

1.Place one meter probe on actuator wire (J1). Place other meter probe on PC board ground wire. Check meter reading.

2.Repeat for J2

Meter Reading	Status	Required Action
OL or more than 1 M Ω		Motor harness OK. Perform PC Board Test
Less than 1 Ω		Replace motor*.

1.Move back section so that it is approximately halfway between its maximum and minimum positions.

2.This test cannot be performed if either base limit switch is tripped. If necessary, remove switch bracket. Switch wires must remain connected.

3.Tag, then disconnect base actuator wires from J1 and J2.

4.Move wire from J3 to J1. Move wire from J4 to J2.

5.Press and hold Base Up button for 5 seconds. Does back section move up briefly, then stop and beep? If Yes, go to Step 6. If No, replace PC Board*.

6.Press And hold Base Down button for 5 seconds. Does back section move down briefly, then stop and beep? If Yes, PC Board is OK. If No, replace PC Board*.