I recently picked up this vintage LeCoultre automatic. Still runs but needs some work. It’s an old bumper, a P812 to be exact. After removing the case back and stem, the movement and dial still don’t want to come loose. I want to be very cautious as this is one of the more expensive watches I have worked on. Could be just a stubborn retainer ring? Or is there a unique quirk of this watch that I’m overlooking? Any help would be much appreciated.