[BarryJB]

Originally Posted by schmidter91

The bit was cut and filed to an appropriate length, which turned out to be about 7mm longer than the stock pin.

I seem to have the identical issue - just had my 915 rebuilt (4th time in 170k & 13 years) and no back up lights when it came back. Shop checked it and said it needed a new switch... but I decided to start investigating today. Switch & wiring is all OK, except the pin (which looks and measures pretty much exactly the same as yours in the pic) sits too far in to actuate the switch - in reverse, the pin seats a good part of a fingertip below the outer machined surface on the gearbox housing & is barely sticking out far enough to reach the back of the switch.

Tomorrow I'll have a buddy move the shifter so I can verify that I will get movement in a suitably lengthened pin (Bosch-derived, thank you!), and take measurements to nail it. Eyeballing, it does look like the pin is about 1/4-in too short, i.e., suspiciously similar to your final 7mm over-stock.

Does this 7mm correlate to some missing or modified or improved part... so far I haven't found a good drawing showing the pin and what actuates it, and I'm unable to visualize the roll-pin as described by RoninLB. At least the old Haynes shows the stepped-diameter pin in the correct orientation.

Can anyone who's rebuilt a 915 transmission explain this?