We have had a report of galling or roughness in the scroll threads causing the timer to stall.

I doubt if the scroll is the  route problem. I have never seen that happen.

The only scroll phenomenon known is getting a burr at the very end where the wire pops off it. The metal gets real thin there and it can get bent easily. In this case, just file off the burr.

In the case where the wire appears to be getting stuck in the scroll thread farther down the scroll, the problem is always the wire itself. In some cases the end of the wire gets damaged by winding the spring up with the wire in the scroll. (Always wind with the wire out of the scroll) The fix is to redress the end carefully with a fine tooth file so it runs smoothly in the thread grooves.  Do check at this point to see if a rough end of the wire has damaged the scroll. Usually, this can be repaired with a small fine tooth file.

Another possible problem is where the end of wire meets the scroll. When at the very bottom, it should be at about the 6:30 position. (Between 6 and 7) Closer to 6 is better. If it is at a position more like 7, then carefully bend the last 90 degree elbow to relocate it.

Finally, the wire may be ridding too hard in the threads. This gets hard to describe as it is a judgment call. A dirty test is to see where the tip of the wire is when it is out of the threads and resting on top of the scroll. The tip should be about even with the inner wall of the scroll. Obviously, check it out with a load on the DT line to be sure the wire will not pop out of the threads.

And a last thought is too much force  being put on the DT post. This is not an issue if it is stopping when there is no load on the DT post. Always use my split rings or something like them on the post to keep the load on the timer low. The spilt ring needs to ride at the bottom of the post. Never put a rubber band or wire or string directly on the post.