I agree with Andy... Of course the best thing would be to disconnect and test each section with a leakage-at-working-voltage checker such as a Sencore LC-101. But if that isn't feasible, here's what I'd do: With the chassis totally cold, power it up. Wait about 5 minutes, and see if the can is warmer than the rest of the stuff around it. I wouldn't want it warm that fast. But if it seems to be cool at 5 or 10 minutes, but then after a half hour it's warm (BUT NOT HOT), that's probably safe. And when Andy says "VENT", that can be a polite synonym for "EXPLODE" in some cases
Charles