Leaderboard

I am not quite sure what happened, maybe you can help with the explanation. In short, I fixed it. It's the pallets. I take the balance out and notice that the pallets aren't locking correctly. I take the pallets out and re-align, install the balance back. That fixes it. However, I am not quite sure what actually happened.

If the balance is not swinging freely, you can investigate if there is a balance stop which is supposed to engage when the crown is pulled out is incorrectly configured. If the balance is swinging freely then you need to remove it and see if the pallets are moving as expected. If they are then the problem possibly with the balance or jewel holes (check the shock system). If not then you have a blockage in the train of wheels. Its a case of process of elimination until you get down to the actual problem. Start with the escapement and work back through the train to the power source. Warning: These movements are quite tricky to locate all the wheels and auto works when re-assembling so make sure you take plenty of pictures and be patient. Go slowly.

Following your advice, I decided to fix the broken stem with a stem extension. After cutting the stem using an end cutter, I use a small oil stone to file down the stem. It takes about three tries to file down the stem to make a perfect fit.