An "amp tech" who doesn't know what a cap job is NOT AN AMP TECH (IMHO)! Find someone else. Or, if you want to tweak the guy a bit, tell him you need your filter capacitors (caps) changed. If he still doesn't have a clue, chuckle as you hang up the phone. A cap job should be done every 10-15 years on all tube amps; it can be neglected longer than that, but come on, some amp maintenance ( other than retubing) every 10-15 years is not onerous. Good luck.