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.

Young hobbyist hoping to get some advice from a watchmaker who is well versed with vintage Longines. The Longines movement in question is this 9L. I have owned a couple watches with this movement before but this is my first time giving one a proper service.
During the reassembly of this movement I encountered a problem with the mainspring. The mainspring winders I have that fit this barrel are unable to engage with the mainspring as the inner coil is too big. I tightened the inner coil of…

HELP! Longines 9L