Thank you all for your response I appreciate your help
it looks like the stem position does seem to split opinions or may not be important.
i will be doing the switch later this week, so I’ll need some luck.
Anyone else willing to offer any advise, I’m all ears and will take onboard.
regards And thanks again
Does the movement actually need to be removed from the case in order to change the position on the lever or do you just need to unscrew the bezel holding the glass on the front of the case? Perhaps it would be useful to post a pcture of teh watch in its case with the case open.
And further to Nucejoe's remark
It could be the Cannon Pinion being loose. It slips at calendar change time.
When changing the time is the crown really easy to move the hands? Often a sign of a loose CP.
Personally, with a screw-down crown like that, I’d just re-use it as is. It may be thread-locked in place.
I always aim to keep them in the inner stem position when removing, but it’s not essential. Gently twist the stem when you insert the new one.