My experiences have always been pleasent. Even though you cleaned the loop jacks, that is only a temp fix. I had my jacks replaced and never had a problem afterwards.
Wolfeman, you really think the caps are going quick on these? I hear about blues guys replacing the caps in their vintage Fenders, since they recommend changing em every 40 years or so, hahaha.
-Joe
Take a look at any modern electrolytic manufacturer, or ask any experienced electronic enginneer, and they will tell you around 20 years is a good time to replace. Like you said about the Fenders, that 'tone' the old amps get is from leaky and failing electrolytics in the power supply. When guys get them replaced, they actually hate it because it changes the tone back to how it was brand new. Bad for those vintage guys, but on something like a 5150 it would make it sound like a brand new 6505. Bad filter caps could also cause surges and spikes, which is what it sounds like some of the older 5150's are experiencing.