Yes, unplug the reverb pan and see if it stops. If you got the cables reversed, you will ground off the reverb drive and it won't be happy. The quick way to sort it out is to pull the cables from the reverb pan, turn the reverb up part way and touch the tip of each cord. The one that hums when you touch it goes into the OUTPUT jack of the reverb pan.
But I fear the damage is already done. Just make sure to figure out which is which before connecting the pan once this is fixed.
ANd you may have got it right and the reverb chip just decided to fail now on its own.
This amp isn't old enough for ALL those caps to fail. Those two resistors get hot because too much current is flowing.
IC1 the reverb chip probably died, so that is the noise you hear when you turn up the reverb. The IC is powered up whether the reverb control is advanced or not, so if it is cooked, it is dragging the supplies down - whuch heats those resistors.
If the power rails are 40 volts, and 30 volts are dropped across those resistors, the 12 volt regulators can't possibly put out their rated voltage.
The trick? After the amp is on a moment, touch each IC on the board - start with the reverb chip just to humor me. The one that burns your finger is bad. Visually inspect the chips. ANy IC with a crack in it is bad. Your power supply voltages will restore themselves once the errant load of a bad chip is removed from them.