It could be your back that is the problem, I have many of them that I never had in my youth, numb hands being one of them, also get them when cycling, I am chasing that problem at moment, different handlebars, seat position, saddle, grips etc. In reality the problem is me! I first noticed the problem when I purchased a Ducati 750S and it killed my wrists. BTW the Vincent must be one of the most comfortable bikes out there, there is so much personalised adjustment available, I love it as much now as I did 56 years ago when I purchased it. GRMS.