The harm. ball. is common for causing the issue and common for failure on the 94-95's. For the stock HB there is an inner and an outer ring with a rubber piece in the middle. This rubber piece will work its way out and either it will be sticking out alot more than the rest of the rubber (not uniform like it should be) or the outer ring will spin and cause it to be off.
Look for the rubber being un-even, or put a timing light on it...if the light looks like its way off (stock is around 10*) then it has spun.
Either way its prob. a good idea to replace as it can cuase some bad wear on bear. and such.
I would also suggest not getting an autozone or like replacement. I went threw 2 or 3 of them in short order. I went with a pioneer unit (non-sfi) a few years ago and no problems since.