Hasselblad a12 sprocket alignment

Not sure how this happened exactly but one of my a12 backs is out of wack. Searched the forums and found out if the sprocket on he film back and body are not aligned, the camera will jam after a few frames. Looking at my working a12 back the gap in the sprocket is always aligned towards the bottom of the opening and this back gives me no problem. The other back shows the gap in they sprocket sometimes in the middle after a frame or somewhere not viewable. Tried to manually rotate the sprocket on the back but can't get it to realign. I assume I'll need to get it repaired but would be great if someone has an easy fix fo this. Thanks!

The film advance mechanism is rather complicated, involving the use of a cam to compensate for the growing diameter of the makeup spool. Problems are usually attributed to poor lubrication or dried grease. The other common problem is light leakage through the dark slide slot. A factory CLA will return the operation to like-new conditions. I feel comfortable firing a lot of things, mechanical or electronic, but I won't touch the inside of an Hasselblad (again).

Make sure you have loaded the magazine correctly. There is a tab which holds the flea against the platter when the insert is unlocked. You must temporarily lock the insert to raise the tab, so that film passes under it. When retraced, the tab keeps film from snagging on the body when the cassette is inserted. If the film is loaded on top of the tab, winding becomes very difficult, spacing is short, and the film may tear and jam the mechanism.

If you really do need service on the A12, a great factory-trained Hassy tech is David Odess in Massachusetts.