Glad to read that as I just fitted my new Alton gear without loctite.
This was necessary when I noticed that the ammeter was sometimes working and then not.
On dismantling I found that the hole in the old plastic gear had grown so much that it would turn on the shaft despite the key.
The only explanation I had for this was that I fitted the Alton without backlash and with temperature rising the pinion grew, more pressure more heat.... you get the picture.
Luckily I have one of these super gaskets thanks to Peter B so this should be an easy job
Bernd
Didn't mention it but yes, I had identical issue about 200mls prior to cover strip down which seemed to rectify itself after I carried out teknikal applied wiggling of wires in headlamp shell to see if there was a loose connection. But I don't see how a keyed in pinion can be loose enough to not drive. I would have thought it would either 'eat' itself or more likely 'walk' of the shaft causing catastrophic damage to the timing gears/motor.
ps have I been using the search function incorrectly not to have been aware that the Alton pinion gear retaining screw was a known issue.