I had a pm1.5 a while back with replacement caps installed backwards! Laugh if you will, but the negative side of the low and mid rail supplies were both backwards. Both caps had vented and the amp was going in and out of protection. The amp suffered from a multitude of other problems as well. It's a hard life on the road.
You mention the amp is clicking. That usually means the amp has detected a problem (the service manual says which ones) and is going into protection. Basically turning itself off. After sitting for a few moments turned off, it forgets there is a problem and turns itself back on only to discover the problem didn't go away. It then turns itself off again. The clicking you hear is the mag coil energizing and denergizing. Your voltage measurements will be unstable when this is happening.
You may get lucky replacing the caps, but if not you will need a variac to diagnose your problem.