The garage door was clunking and was erratic in adhering to the “limits”, that is it sometimes banged against the stop when going up or down, instead of at the programmed point.
The service guy told us that the mechanism that sets the limits was worn and couldn’t be repaired so the only option was to get a complete new motor. Somewhat reluctantly, we agreed to this and in due course the brand new motor arrived and was installed. Needless to say, technology has moved on, so we also got a new chain mechanism. However, the results are great: everything is much quieter and smoother.
As he was leaving the technician offered me a word of advice: the mechanism needs to be serviced every year or so. The reason for the wear in the old motor was because the various components, such as the door springs as well as the operating chain, had got out of alignment, thus putting extra stress on the control mechanism.
Lesson learned: devices such as this need to have a little loving care now and then!