Sunlight wash-out is a very common problem here in sunny SW Florida.

Sears would have the capacitor if the people there know what they are
doing. Around here if you don't have a Sears part number they usually
can't help you. Any Liftmaster dealer should also have the part.

You could probably also get the capacitor at any motor shop or
Grainger, however while the rating may be the same the actual size
(diameter) may be different & therefore may not fit in the original
holder. The rating on yours should be printed on the side w/ something
like 220 VAC, 53-64 MFD. It's ok to go up on the VAC rating, but the
MFD should be as close as possible.

Doordoc