I have a 1969 Ampeg SB-12 that was given to me blowing fuses. Replaced all of the filter caps, powered it up with a current limiter and the bulb lit bright after hitting the standby switch. I removed all of the tubes including the rectifier tube, current limiter bulb did not light when coming off of standby. Inserted rectifier tube (known good tube), without any other tubes and the bulb lit up. Disconnected the newly installed filter caps and bias supply from the circuit, bulb still lights up! Damn.. Disconnected B+ to the CT of the OT.. Bulb does not light! I measured the resistance on the primary side of the OT and I'm only measuring 30 ohms from the CT to chassis, 170 ohms from pin 3 to chassis on the first 6l6 and infinite resistance from pin 3 to chassis on the other. Sounds like OT is done to me.. Is there anything else i can possibly be missing? Thanks!