Just picked up a jtm45 clone and amp is running very hot. Also breaks up very early on the volume pot, at 11 o'clock. I checked the bias at the external bias terminals and they read 124mv and 119mv with the KT66's in it. I changed tubes to 6l6 and readings were 99 and 95mv with external bias pot all the way down. Any ideas what could cause this? Could a bad rectifier tube (5ar4) cause this?