Here is a great Basic training subject. There are many players complaining about these new Reissue amps developing a high frequency squeal. Most assume it is coming from the reverb tank or a defective preamp tube. There are many writeups on various music websites recommending all kinds of hocus pocus, juju bones, tarot cards. Most of it is bad information that will send you down a dusty rabbit hole. Well, I have news for you, more than likely its due to power supply issues. These amps are loaded with IC (Illinois Filter Caps) which are know for premature failure. More than likely batch issues, however I cannot verify that. In my experience, it is always best to remove the violators and install a quality set of F&T filter caps. You can purchase these caps form Amplifiedparts.com. I go thru them like candy. Yes, normally I do not work on these reissue amps, however I am hearing all sorts of interesting failures and it intrigues me. So, I will probably take on a few more so that this information can be shared. Thanks to all of you for recent tube & $$ donations to support my shop.