I've found a few leaking caps (gunge), the big dual cans, on several 545B's and other 500 type scopes. Also found some of the Sprague coupling caps to be leaky, electrically.
Having had experience soldering these ceramic wafers you can solder with normal 60/40 solder, havn't had any of the tags come loose. This is just touch up work though, I did use some 3% silver solder added into the joint occasionally to be on the safe side. You have to use a very hot iron also. See here -
https://www.youtube.com/watch?v=RpB5JqGo1co for guidance, it also gives info in the 545 manual.
Andy.