Back Up Light Switch Engagement Conundrum

Wow, I have been away from this website for a long time!

I am deep into the process of a meticulous teardown, cleaning, and rebuild of the iron case 833OD that I swapped into my Valiant two summers ago. I just started reassembling the transmission yesterday evening. After installing the entire reverse assembly, I actuated the reverse lever to ensure proper actuation of the mechanism. At this point I noticed that the reverse lever does not rotate rearward far enough to contact the ball which closes the back up lamp switch--there is probably a 0.060" gap, and stacking feeler gauges indicated about 0.082" of extra rearward motion would close the switch.

Long story short, after making a couple of calls, it was suggested to me to turn down the gasket seating face of the switch with a lathe to increase the protrusion of the ball end into the case. However, after speaking with my machinist, it was clear that he was hesitant to turn the switch for fear of weakening or breaching its already-thin, hollow metal case. He instead suggested deeper inspection of the whole assembly to see if I missed anything. In taking his advice, I determined that the true cause for the issue is that the reverse lever is prematurely contacting the tip of the large detent plug that houses the reverse spring and ball.

So now I'm stuck trying to decide what to do. Do I file on either the reverse lever or the detent plug tip where they interfere (risk messing up the otherwise good engagement of reverse gear), or do I put a tiny weldment onto the end of the reverse plug (don't really want to weld on the lever shaft) to fill the gap space?