Hello, all I'm in need of a replacement tuning cap for my SB-220. The stock original Heathkit p/n is 26-131. I do NOT want this... the one I have has arced over and melted some of the plates! The unit I want is the stouter replacement for the SB-221, Heathkit p/n 26-164. Any leads would be appreciated. Vy 73, Charlie N9CO