[MRCA] RT-524 Repair Question

[Radio Station KW1I]

I have a pile of hard copy and online PDF RT-524 manuals, but I can't seem 
to locate a suspect assembly.

The RT-524 when powered on has no audio, the lights don't work and the 
blower is on even though it is not transmitting.  There are two circuit 
breakers on the back of the front panel.  One is a 15 amp that feeds the 
A9000 power module and the other is a 1 amp that feed a R2100 Regulator 
Ass'y and the indicator lamps.  The 1 amp circuit breaker unpowered has a 
very low resistance between the supply and load terminals.  When powered up 
the load terminal reads less than 1 volt.  I am looking for the the R2100 
Regulator Ass'y so I can check it out, but cannot locate it while inspecting 
the rig or in my pile of tech pubs.

Help.