There are caps dumping in that channel. You must have a bleeder resistor to ground in parallel with the supply caps to stop that from happening. My guess is you should be looking for 5.6k or so and it should have a big and fat 5W body. There should be at least one for each phase of each channel. "Why is it in only one channel" is a very good question though. It could be that you have a bad ground on that channel's board - if it's designed that way. You can also check the grounding scheme by measuring the resistance from the IEC socket ground pin to the chassis (find an unpainted location). If it is chassis grounded (< 100 ohms), I bet you have a black wire that is loose on the left channel board. If not, you will probably need a schematic.... Feel free to ask me questions if you need more info.
When you say "you" bridged it, did you just flip switches or did you rewire it?