Quoted from RonSS:While I was replacing some plastic, one of those star acorn nut things dropped into the cab. When I retrieved it, my gorilla hands definitely banged up against some of the internals.
That would be a good start. Compare, and look for things that look bent, out of place, etc. Very good idea to only work on the known problem and not create new ones.
Oh, and hi, and welcome to Pinside!