do you have a clamp on ammeter?
just put all the tubes in, with everything stone refridgerator cold at 4 in the morning, measure the primary current after a 5 minute burn in.
then unplug the beastatron, measure the primary resistance.
then apply ohms law for heat, which will be primary current times primary current times primary resistance.
see what you get.
this is inexact science do to all the pwr factor voodoo and mag currents vs saturation levels, but it should give you an idea if you are pushing the copper beyond it's current carrying ampacity.
then pull all the tubes, put the ammeter back on the primary, get a piece of paper and draw an x-y graph with primary ac current vs tubes put in.
you do not want to mess with breaking the B + line and inserting a ammeter, bad things seem to happen when i do this, like expensive meters fryng.
we just want to see if as the tubes are inserted, all of a sudden there is a jump in pri current.
this would indicate saturation, which means the lams will generate heat as well as the
copper loss.
ok, here is a faster, safer and easier way.
wire in a light bulb socket, 120 style lamp socket for your house, get a nice ceramic one from china, wire in a 120 watt bulb in the pri circuit.
then remove all tubes, insert them one by one, and see what the bulb does.