If one edge of the barrel cap has lifted or popped out of its seat it could drag along the pillar plate or bridges or even hit the center wheel. This can actually stop a watch. This is a very common problem and can sometimes be difficult to diagnose. Look for wear or scratch marks along the barrel cap surface. You can check to see if there is any contact between these surfaces by removing the pallet assembly and allowing the train to spin slowly.

It’s important to remove the hands from the watch before allowing the train to spin and to also regulate the velocity of the spinning train by applying a small amount of pressure to the second or third wheel with your finger tip. If allowed to run freely backlashing of the wheel teeth may occur which can sometimes cause damage to fragile train teeth, pivots and or jewels.

Again, barrel cap problems occur often. It may just be that the cap was never pressed firmly down into its barrel seat. If the cap can be pressed in with a snap you will probably be ok. If on the other hand it just will not stay seated then there may be a more serious problem.

Check that the mainspring is sitting all the way down inside the barrel and that the entire spring sits below the barrel cap seat. If the spring does stand above the cap seat and can not be pressed down below it then the spring may have been replaced with one that is too wide. If this is the case then it must be replaced with one of the correct size.