I haven't had to repair any of those so I can't answer your question. If no one else replies, try asking earthquake. If they won't help, you may be able to find a corresponding component in another area of the amp.
That configuration is used in virtually all of the amps (sony, mtx, xtant...) that use a driver transformer. The resistor is likely there to control the undriven winding in each half of the drive cycle.