There is sometimes a lot of drama when a tube fails catastrophically.   Fireworks, noises, etc.  So did the rectifier just blow or did something else take it out?  So put on your CSI cap.  I would pull all the tubes and with no power applied ohm out the high voltage caps and resistors in that part of the circuit.  Drain the electrolytic caps first.  Check for shorts or low ohmage across the filter capacitors and resistors that may be burned or out of tolerance.  If it looks good at this point put in the new rectifier (no other tubes) and check voltages.  They will read high without a load if all is normal.  Then install the remainer of the tubes and see if it functions OK.  Flakey power tubes could cause the rectifier to pull too much current and shorten its life.  Check for red plating in a dim light.  If something does look right stop and analyze, get a 2nd opinion, or ask a question.   I trust the tech that worked on the amp is competent.  Fresh power tubes could draw more power and stressing the old rectifier I suppose and hastened its failure.