picked up a 1978 peavey mark III half stack. it has a bit of rumbling (yes i've isolated it to an electrical problem as it runs fine with other heads). im thinking to replace the fuses, also if the problem is in the circuitry related to the channels then would using my crate 30watt as a preamp fix this problem seeing as id just use the peavey head for the 130 watt power?
rumbling as in buzzing? if thats the case i think the most obvious solution would be to replace the tubes in it seeing as its an older head and if the tubes have been in it for a while that could easily cause some buzzing. otherwise i have no idea, im hardly an amp tech.