As we discussed somewhere in this thread, the manufacturers added a relay so the SCR wasn't directly switching the full solenoid current, that could be an option if you are regularly blowing SCRs, but as I said the fact that it pulls in for 5 seconds suggests that the main SCR is (probably) working.
So just so I'm clear what's happening - are you saying that you are continuously welding for those 5 seconds and the revs drop back to idle in the middle of your weld?
So just so I'm clear what's happening - are you saying that you are continuously welding for those 5 seconds and the revs drop back to idle in the middle of your weld?