So I get this watch. It runs OK, at least kept decent time overnight on the bench. But, it is full of gunk and grease and grime. SO, I service it. Now, the action is SO GOOD that it hits the other side of the pallet lever and.... well, you know the rest.
My question is: Does this automatically point to too strong of a mainspring, or could it (likely) be something else?... Thanks in advance

I'm not sure exactly what it is doing, James.

If it is hitting to one side, it probably means that the hairspring is not centered. In those cases the hairspring collet needs to be moved to center it.

Have you timed it?

I think it's called knocking the banking,or something to that effect. Have you measured the mainspring to see if it is the correct one for your watch?

Maybe I didn't explain this very well. Many would call this "overbanked". But, I've read here that may not be the most correct term. The roller jewel is ending up outside the fork. The balance appears to have quite a bit of rotation. I would say well over 270 degress. Does that explain it better?

It's very difficult to diagnose a balance problem without the watch or at least pictures. But... before you touch the banking-pins, try this.

Try to stop the balance with wind on. Find the neutral point of the balance wheel where the hairspring is not pulling the wheel in either direction. The wheel should stop in that position. Then look at the pallet. The pallet whould be absolutely straight... not pointing towards either direction. If it is not straight, then the hairspring is out of position and needs to be moved. The "neutral" point of the balance wheel should also be the neutral setting of the pallet.

I would just tighten up the banking pins "IF" it was a South Bend PW. Peter's explanation above will show you if the hairspring is centered correctly. If it's not you'll also have a very bad beat. There's lots of reasons for a watch "going out of action" (that's the oldtimers term). Among them:

1. Excessive side shake in the balance pivots or pallet arbor pivots.

2. Excessive end shake of the pallet arbor and balance staff, allowing guard pin to pass over or under the safety roller.

3. Short guard pin that passes by the roller.

4. Loose guard pin.

5. Missing guard pin and/or roller table.

Good luck on fixing it!

Frank "407" Kusumoto

Thanks for the suggestions, but I am still fighting this. I should add that this happens while sitting dial up on the bench. Only once did it happen dial down. Approximately 60 sec after I turn the watch over, it overbanks. I should also add that it always occurs with the balance on the same side. I did verify that the hairspring stud is in the correct position using Peters suggestion.
From some of the suggestions, I suspect some of you believe this is happening while being carried. Maybe this additional info can give you a clue for further suggestions?
Thanks again

I got it! Thanks to everyone for the suggestions. I eliminated everything but the banking pins. I decided to open the one up just a hair, and it worked!
I think maybe the pin moved in the ultrasonic while cleaning. Has anyone ever seen that happen? The threads didn't seem overly loose, but not nearly as tight as some I've seen either.

Thanks again, Jim