Genuine LiftMaster K41-0387-000 encoder, supplied with drive sprocket, snap ring, mounting plate and screws for the Maxum industrial DC operators.
Fitment: LiftMaster Maxum JDC, RJDC, JHDC, TDC.
A failing encoder shows up as limits drifting or the door stopping short.
Ordering the right part depends on the full model number, which is printed on the operator label. Call GateHouse Supplies if you are not sure — we service these units every day.