I had a little detour before powering up the 400 with the new WOA control board. While waiting for the exchange of the variac I fashioned extra cooling fins. I found 1 x 6 aluminum channel on they bay. After cutting off one edge I was left with the perfect size to become a pair of fins. I drilled and tapped some 10-32 holes in the back of the chassis. Ran some 3/4" screws through the holes to create some mounting Studs. I'll need to cut down the output transistor covers. It's got to be better than nothing.