I have some knowledge of amplifiers specifically AL-811's rebuilt one in fact new circuit board, Parasitic board, Band switch back plate and bottom plate due to damage in shipping or it was dropped. That was easy. Did the grounded grid mod on an AL-572 and aligned the input coils as well. This SB-220 I am being very cautious around. Manly higher voltages etc. and I don't want to ruin the 3-500z's. Plus the original builder did a good job. Whoever owned it next put some mods in that I removed and the soldering was iffy at best. Could literally pull the wires out of the meter board. Really bad soldering job so have been slowly checking it over. Also I notice the top of the plate caps are very close to the inner metal screen. Is there a chance of arcing. I know someone put some kind of Corona paint? on the inner metal screen in the area of plate caps. Just wondering. If there is a chance how can I prevent it? I was thinking of ordering the low profile plate caps like Ameritron uses in the AL-80B. Better to ask lot's of questions of the experts here like you WB2WIK, Steve, Sue and others than be sorry for it later.