LiftMaster SW420 SW420 S3 BOARD Manual - Page 30

30 Troubleshooting 5. Gear Reducer If physical signs show a seal has broken in the gear reducer, it may be necessary to replace the reducer. When replacing the gear reducer oil, use Mobil1 10W-30 synthetic oil or equivalent. The oil level for the gear reducer allows gear to be dipped but not submerged in oil. DO NOT overfill gear reducer oil reservoir. Reducer oil - Part #04-20009 General Reference Information THE GATE Double check the gate and its related hardware. Does the gate move freely? If it doesn't, this can affect the internal obstruction sensor. WIRING DIAGRAM Always reference the wiring diagram that was supplied with the operator. Note that some of the accessory items may have their own wiring diagram. If you cannot correct the problem or if you feel you will require technical assistance, contact your local distributor or dealer. If you do not have a distributor or dealer, then contact us for technical assistance. Please when calling for assistance, make sure you have the gate operator model number, voltage, phase, horsepower and a list of all accessories that are attached to the operator. Features and Program Troubleshooting Review The internal obstruction sensor (r.p.m. sensor) will cause the operator to either stop or reverse if it senses a slow down in gate speed. A damaged or poorly working gate can trip the sensor and cause "phantom" reversing or stopping. Doc 01-G0610 Rev A