I have a pair of BA racked Calrec PQ1061's that I might be purchasing from a buddy of mine. He purchased them new from Brent 20 plus years ago. Cosmetically, they are in great shape and have lived their life racked up in a studio. The switches were scratchy so I popped the lid on one, then the other one, and they both have the same thing going on internally....LOOK at the rust on the pots and the corrosion. What would cause this? I have never seen anything like this before,and wanted to see if anyone has? Also, does anyone know of available parts that I could replace these with? Thanks in advance for any/all input at all regarding this!