Congrats & nice job!
I also had a similar VUK problem on my Star Wars a month ago. Ug.. Sorry I didn't make the connection and save you some time.
In my case, a triangular section on the sheath of the yellow plastic cap had cracked free and was causing the cap to wobble. Sometimes the cap would get jammed at an angle and the ball would never trigger the switch. I put in a replacement VUK kit — plastics, spring, ring clamps (whatever they are called) — and all is well again.
Post edited by cheezywhiz