Well, since it's over twenty years old, I'd say that a little nit picking would probably be good for it.
First of all, keep the fan clean and the insides as well. As the fan blows to keep the guts cool, it blows in dust and stuff. I've been told that this layer of dust creates areas that trap in moisture which, of course, hurts the amp. So, I'd peek inside every now and again just to see how it's doing.
Second, I would suggest putting it on top of a couple layers of carpet padding or something to minimize the amount of shock the amp takes. I've almost rattled amp heads off my 215 cabinet before, so there's a significant amount of shock coming up from there. That will help keep stuff from rattling loose.
So, those are the things I do. I'd gig with it for sure. Maybe not every single gig if you play frequently, but what's the point if you can't play with it?
