Greetings...does anyone know the proper mainspring replacement number for a 21j 16s grade 105 model IV
hampden 1903 movement,actually a little stumped on how to let down the mainspring on this one,the ratchet and winding wheel are covered by the bridge plate and I see no release holes at side of the movement
Mark

Mark,

I believe the factory number is 3696 w/ a T-end

Thank You Jon

Mark, as the click and click wheel are under the dial on this bridge movement, the release is in a hole on the rim. If I was letting this one down (meaning the mainspring is still intact), I would take off the dial, giving direct visual access to the click so you can let it down pretty easily.

Thanks guys... I have two of these in line for COA... knowing to go under the hood to let down the main spring is quite helpful.