I am currently in the market for a vintage Princeton Reverb. One has just come up on my local Craigslist and I am extremely interested. Does anyone have any tips for me when I go check this amp out? What kind of questions should I be asking to make sure this amp is in great shape? What should I be looking for when I examine the amp? Also, this amp in particular is a silverface, non-reverb. Any help would be greatly appreciated. Thanks!