For opener calls in Georgetown we carry the parts that fail most on units this age: drive gears and sprockets for chain and belt systems, logic boards for the common residential brands, safety sensor pairs, and wall control units. We also carry backer board and lag hardware for remounting into old framing, since that's as common a fix here as the motor itself.
What we don't carry on a first visit is anything specific to a header we haven't seen - if the framing needs more than a backer board, that's a return trip once we know what we're building into. With 1,302 households in this pocket of the county, most of them in houses from the same build era, we've got a decent sense of what shows up, but we're not going to pretend every job is the same one twice.