What to look for in a used amp?

Hi there, I'm going to look at an alpine mrp-m1000 to run with my 2 10" kicker slims. I'm just wondering what kind of stuff i should be looking for. I've already been told to smell it, power it up, check for black terminals, and check the gain to see how hard it was pushed. Is there anything else i should be looking for that would indicate problems or potential future issues? thanks