A strange slipping sound/jerking sensation

Assuming you need to replace a gear and selector fork , the bottom crankcase will need to be removed to get the gearbox shafts out.

 

Do you know the best place to purchase gears?

 

Any honda main dealers can order the parts for you or order online from example below.
https://www.bike-parts-honda.com/honda-motorcycle/1000-MOTO/CBR

 

I'm having the same issues with my bike (cbr rr-5) in 2nd gear. Think I'll be taking my gearbox out to investigate. Nova Raving apparently is a good place to get gears rather than replacing with original honda, they seem to have a good reputation for racing gearboxes

 

I believe the 929 & 954 use the same box , if looking for S/H