Can't find that schematic now, but those modern Randalls often have a thermal mute built in.
Not mechanical (bimetallic) but a PTC type thermistor which when hot cuts power to the power amp input stage.
You *might* bypass it, but it would be a dangerous move.
Cooling is never bad, so I'd add a little fan there.
Post a couple chassis pictures, inside and outside, maybe you can add two.
Check this RG75B schematic.
Thermistor RT1 (PTC), through Q4/Q5/Q3 cuts current to differential pair Q1/Q2 , muting the amp.