OK been playing with my Super 5f4 build that I got back from the tech after he got most of the issues resolved that I had. The Chassis was a Amp out of a Hammond Tone Cabinet I gutted out the chassis and used the Hammond PT and a Peavey OT. Mostly he had to redo the bias circuit for the negative feed back circuit because the PT I had did not have a negative bias tap since this amp was made from old iron. Two the filter caps had to be replaced as that negative bias issue blew one of the filter caps and weakened the rest or it could have been the voltage issue that described in a bit. I had built a circuit for the bias taken from a fender amp but it did not give a high enough bias voltage. Second issue he had to fix was the PT was made for a lower Primary voltage it said 110 instead of 120 so that made the secondary Voltage higher which also may have been an issue with the filter caps. He resolved this with a couple of heavy large wirewound resistors. Third was replace a couple of tubes that may have been iffy. Ok now he gave it back and it sounds really good except for the following issues. The treble knob if turned up to almost max squeals or feeds back. The Volume pot if turned to about 8 seems to cut out then if you go past that you get a motorboating sound through the speaker. Note this is only on channel One Channel Two seems to work fine with both controls maxed. On issue is the first Preamp tube V1 is a 12ax7 as I did not have a 12ay7 to put in that spot. The tech did not have any at the shop but was looking through his stash at an other place for one. Could the 12ax7 just be overdriving that first channel? Or any other suggestions where to look. One thing I thought of is the input jacks are just grounded to the chassis using the barrel of the jack would running a ground to each jack be a good idea? They are switchable jacks.