Grant's original problem sounds to me as though either the G101 bush is well-worn, allowing G46 to tilt and thus not engage properly, or that a new G48 spring is needed. Or both. If G82, the kickstart ratchet, does not fully engage with G46, then it tilts unless G101 prevents it. I made a bronze G101. The original was oilite, had almost worn through. Francois Grosset told me that he has seen G46's that appear totally wrecked, no single tooth intact, but that still grip perfectly. However if G46 tilts...then it's best if you planned to have no more children anyway. Please do not ask how I came by my knowledge. They say the memory of the intensity of pain fades: they lie.
Robert Watson says he just kicks and drops the lifter. Robert however won't mind me saying (I hope) that he is A BIG CHAP, and I am not. It took me an age to find the right technique for kicking. It turned out to be to find the SECOND compression, DO NOT ease over, lift valve lifter, kick and drop lifter almost simultaneously. Prior to this I'd religiously eased it over both compressions, delivered the traditional LSK, and 9 times out of 10 was rewarded with the deafening silence that attends a Vincent failing to start. Then my knee would begin to give notice to quit. Which is why I now start courtesy of la jambe de grenouille, and merely press the red button. Or le bouton rouge, as you prefer.