Working on a Marshall 4101 combo, JMP 50C board. Just recapped the whole amp. Retubed with JJ EL34's. Bias at 32 ma at 440V. All my voltages are right. 100 ohm and 22K resistors at in line with the caps are spot on. Amp cuts out after been on for 30 min. Filter caps at 200 degrees!! I used F&T 50+50 @ 500V. Did I get some bad caps? Screen resistors are good running 435 screen voltage.