Well, it was going well until... I've had this old Swiss 12s / 18 Lignes movement running at my desk for some two years. Then the mainspring gave way. I ordered a replacement New York Standard 16s spring for a replacement. It came. Today I put it in and wound the movement... only to have the center wheel pinion spin loose of it's press fit on the center wheel gear. So now the repair is beyond me. Oh well, too bad as it had a good balance staff. This movement I assume has been worked on a lot since it looks like somebody put jewels in the top plate while the bottom plate has no jewels. Sorry, I don't have a picture of the center wheel and the problem. The center wheel had a large whole in the center so that the center wheel was pressed right over the pinion gear. I first thought it had been repaired but the next wheel down was made the same way. The pinion gear leaves look like they dug into the brass wheel pretty good. This Waltham center wheel looks similar except my center wheel pinion is all one gear. No step for the center wheel to press on to. Anyway, I guess the only hope is to find a center wheel now. Probably isn't going to happen, especially for an old keywind Swiss movement.