Ok here goes..... I got interested in nos tubes and after careful research I purchased a few 12ax7's and 5751's and put them in my harsh sounding 100 watt carvin v3 guitar amp head. Oh what a difference nos tubes make! So after that experience, the money wheels in my head started turning. So, I rolled the dice on eBay and lost. The seller stated that the unit powered up and the needle centered and said that it looked like it might work. Well, it does that just fine, but it reads all tubes as bad. FYI, the settings according to the roll chart were set properly. Any body know how or where to get this thing fixed?

Thanks,
Slow Short Bus

Correction. I can real my 6L6 power tubes fine. The 12ax7's all read as bad. Cap or diode issue?

Socket or tube issue? Dirty switches?

Used multiple tubes, cleaned switches an socket.

The biggest problem Ive had with my Jacksons were the worn pins on the sockets. If they dont all grab snug you will have to replace that 9/10 combination socket. The only place I have found them are from a seller on Ebay from Canada at 10 bucks a pop plus shipping. If it is reading your 6L6 tubes correctly it should be able to read the others. Poor pin contact can give false bad readings. You can alternatively replace it with the more common 9 pin socket or add a 9 pin to your array.