BJ III blew fuse 1. Replaced fuse, noticed crackling in power tube. Replaced power tubes. Now amp has crackling sound when played. Also humming sound at any volume and even with no input. Also resoldered all tube bases. 2. Replaced preamp tubes. Problem unchanged. 3. Replaced 4 large IC capacitors. Problem remains unchanged. 4. Poking around board/tubes with chopstick has no affect. anyone have any other suggestions?