[Amps] Dentron MLA-2500

[Roland AH6RR]

Aloha All,
I have a MLA-2500 that I have done a tube swap to the Russian GI-7B. All was in good working order for over 2 years until I decided to build a airbox around the tubes and had the Watt meter sensor to close the plate choke where the high voltage jumped to the sensor board and killed the meter and board. It also took out half the diodes on the voltage doubler. I replaced the diodes and took the sensor out. But now it keeps blowing the same 6 diodes on the voltage doubler on 40 Meters. Seems fine on 20 meters with 1200W with 350 mils of plate current out but when I switch to 40 it will work for about 2 minutes then the fuse blows. I check and the same 6 diodes on the Plus side of the doubler are shorted.
 Could this be the caused by one of the filter caps being weak or could it be one of the tubes. I checked the tank and all seems fine there. Any help would be appreciteated.

Roland AH6RR