We start by running the opener through a full cycle with the door disconnected from the trolley, to isolate whether the fault is in the motor, the drive mechanism, or the door hardware itself. On the chain and screw-drive units common to houses built around 1980, that usually means checking chain tension or drive screw lubrication before anything else. From there we test the limit switches, check the circuit board for burn marks or corrosion, and confirm the safety sensors are aligned and wired correctly.
If the fix is mechanical - gear, chain, switch - we handle it same visit in most cases. If it's electrical and the board needs ordering, we'll finish the mechanical side first so the door operates manually while we wait on the part.