Hey Dave,
That model had a couple of 'weak spots' that frustrated the devil out of many hams who bought them new 25 or so years ago. On the circuit board that has the transmit driver on it, are a handful of "DIP"-type relays that will become intermittent. Not if, but when. If they have already been replaced on your unit, that's great. Like buying a 1980 car that has already had the original A-frame bushings replaced. Possible, but not too likely.
If the transmit and/or receive start to cut in and out, and if the preamp works "sometimes", odds are that you have "DIP"-relay trouble. They are a pain to replace, even IF you can find them. Used to buy them from Digi-Key, but they replied "DISCONTINUED" last time I tried to reorder a batch.
If it's a good one, it's a good radio. If the seller sold you a radio that needs relays, it's your problem now.
73