Just an FYI. As I'm restoring an old K6100 powered speaker cab and K6002 preamp head the reverb didn't work. I could here a slight bit of reverb at max volume but not much. So a reliable source told me that it was common for those reverb tanks to have weak connections even when the soldered joints on the RCA input/output AND the little transformers at both ends of the spring carriage meter out fine for continuity. So, I touched them up last night with a solder pen and voila, its working just fine.

MARK in Boise: Didn't you have issues with yours? If so, you have to carefully remove the bottom cover of the tank which is only held on with double stick tape(at least on mine). Touch up those connections (8 in all) and retest!

Good luck and let me know if it works out.