The odometer stopped again so I pulled the panel out again to find that the spur gear had again travelled along the odometer shaft and out of engagement.
This time, it was in much better light than before and I could see why. There is a hairline crack through the gear which reduces its grip on the shaft, allowing it to ride outwards and out of engagement. As an interim fix, I will try some Loctite if I can find some. My stock is locked away in a colleague’s workshop until 10 Jan.
But I have a problem. Phill says that the 2WD speedo is different so this gear is likely to be different also.
The gear is 12.4 mm diameter, 2.0 wide, has a 6.0 wide boss and has 10 teeth; the spindle is about 3.0 diameter.
Does anyone have an old Syncro speedo that might yield a gear?