I just received an older inexpensive (Maeda Industries) 5-speed freewheel I purchased on eBay. Overall it appears to be in good condition: teeth not significantly worn, spins smoothly & freely - but there's the distinct sound of a few loose bearings rolling around inside when I tip it back & forth.
Without taking the thing apart, is there a way to tell if this is a problem? My guess is that I ought to return this to the seller - or, is this not an uncommon occurrence & therefore a low-risk situation?
I agree -- lube it and leave it. There is no reason to disassemble, unless you like chasing 100 tiny ball bearings across the room. Freewheels were assembled at the factory with oil rather than grease, and a little more oil will fix the problem if there is one and won't hurt if there isn't.
Please note that you got two contradictory opinions from Knoxville. That must be significant somehow.