peter, if it is a mkI in a sunwatch case, it probably doesn't have gel in it. whoever built it would have had to open the mkI and remove it from the red top and do whatever necessary to restore it. then drop it in the sunwatch red top and close it up. still, if you have mkI parts and understand the workings of it, i would recommend building one of those and get a top, bottom and s/s case. as ed said, opening a working synchronar just for that is quite risky. i'll agree to that.
i have rebuilt 14-15 of them, but not all 100% successful. i still have some left for a rainy day, but we don't get those in aridzona.
. peter