Welcome to EAB MoogleLally
First question, have you asked him if there has been any repairs done to the Amiga, as in, anything replaced on the mobo?
You see, the caps are definitely on there way out 'n' probably leaking, if they've never been touched, so before you sit down to some serious gaming with it, I would suggest replacing all the caps on the mobo, or you could end up with an Amiga that's just collecting dust.
Some of the guys here will tell you exactly what you need to do and how to check properly, but please, don't power it up until you know what state it's in. Open her up and take some pics of the mobo and post them here if you're not sure whether it's OK or not