I have Traynor 40 watt amp. A while back my son was digging on it and it blew. Power/ sound gone. I naturally thought he blew a fuse. Took it to my local guitar guy. He replaces the fuse and the power tubes. he put in sovteks. But! now no reverb and the standby switch doesn't work either. repair guy says he has no idea why that is. Any thoughts and/or suggestions?