Liftmaster Arm Parts LA400,LA500,Miracle Arms
LiftMaster Actuator Arm Parts — LA400, LA412 and LA500
Complete replacement arms and arm components for LiftMaster LA-series linear actuator swing gate operators. Use the exploded view above to identify the component you need, then click any part number to order.
Before you order — three things to check.
1. Primary and secondary arms are different parts. On a single gate you need only the primary. On a dual gate you need a primary on one leaf and a secondary on the other — the secondary carries a longer cable and cannot drive a gate on its own. The DCS suffix marks the secondary: LA400DC and LA400DCS, LA412DC and LA412DCS, LA500DC and LA500DCS.
2. The arm components are shared across the whole LA family. The release lever, motor with limit switch harness, rear connector, release key and hardware kit are the same on LA400, LA412 and LA500. Only the complete arm assemblies differ between models.
3. K77-19130 and K77-19130-1 are not the same kit. K77-19130 is the standard hardware bag with gate bracket, post bracket and pull-to-open bracket. K77-19130-1 is the two-post bracket kit for LA400 and LA412. Both are stocked and this is an easy wrong order.
If you need the control box rather than the arm, see the model pages linked at the foot of this page.
Which Part Do I Need?
| Symptom | Usual cause | Parts to check |
|---|---|---|
| Arm hums but does not extend or retract | Motor or limit switch harness | 041ASWG-0438SA motor with harness |
| Gate will not release by hand | Release lever or lost key | 041ASWG-0442SA lever, 041ASWG-0119 key |
| Arm loose or knocking at the gate end | Rear connector worn | 041ASWG-0014SA rear connector |
| Intermittent operation, arm stops mid-travel | Cable damaged where it flexes | Motor and harness assembly, then the arm itself |
| Arm bent, seized, or leaking | End of service life | Complete arm — match your model and primary or secondary below |
| Brackets rusted or gate post changed | Mounting hardware | K77-19130 standard, K77-19130-1 two-post |
Complete Actuator Arms
| Ref | Part # | Description |
|---|---|---|
| 1 | LA400DC | LA400 Primary Arm, 24V DC — single gate, or the driven leaf of a dual gate |
| — | LA400DCS | LA400 Secondary Arm, 24V DC — second leaf of a dual gate |
| — | LA412DC | LA412 Primary Arm, 12V DC |
| — | LA412DCS | LA412 Secondary Arm, 12V DC |
| — | K-LA412 | LA412 Primary Arm — current replacement |
| — | LA412UL | LA412U and LA412UL Single Arm |
| — | LA500DC | LA500 Primary Arm, 24V DC |
| — | LA500DCS | LA500 Secondary Arm, 24V DC |
| — | K-LA500UL | LA500, LA500U and LA500UL Replacement Arm |
Arm Components — Shared Across LA400, LA412 and LA500
| Ref | Part # | Description |
|---|---|---|
| 2 | 041ASWG-0442SA | Release Lever |
| 3 | 041ASWG-0438SA | Motor with Limit Switch Harness |
| 4 | 041ASWG-0014SA | Rear Connector |
| — | 041ASWG-0119 | Release Key |
| — | K77-19130 | Hardware Kit — gate bracket, post bracket, pull-to-open bracket and hardware |
| — | K77-19130-1 | Two Post Bracket Kit — LA400 and LA412 |
For control boxes, boards and the rest of each operator, see the LA400 parts, LA412 parts and LA500 parts pages, or the full LiftMaster gate operator parts catalog.