All my classic bally sterns get a new rectifier board at the first sign of a problem. If you repair the old ones you'll end up chasing your tail as new problems invariably pop up (as you have discovered). Weebly.nvram.com has lots for around 40 bucks or you can get a completed one for around 80ish. If you want to save the ducketts and just fix the one problem check br3. Negative multimeter probe to positive and positive to each AC one at a time, should be around 5-6, then positive multimeter probe to negative bridge, negative probe to each AC for the same result. You can compare to the other bridges to verify your testing method.

Good deal! For future reference the DMM should have been set to resistance for the above test, sorry I left that crucial element out. As an individual component test the game should also have been off. Glad you didn't get zapped