Hi JW; have you seen/are you included in This? Good idea on the tapping; will ID a cold joint or maybe a tube with a loose internal connection. I once bought a Guild Thunderbass head off eBay; the seller said it 'works if you shake it' ... he was right ... one of the output tubes rattled! JJazzWest said:Also, I purchased a '66 Ampeg Gemini II of eBay a while back. The seller packed it very well, but when it arrived I heard something rolling around inside the amp's cab :shock: After I unpacked it, I saw the main filter can cap completley torn out, out on a joy ride.