AJSP is your best bet - you also should check that no engine mounts are broken and the engine alignment is good.
cheers guys tried AJSP they dont do the long shaft as an aftermarket part anymore, only the short one. Genuine yamaha seems the only option.
... as a less expensive option to a new one... can shorten down and get a spline cut on a 2nd hand shaft from an old waverunner which are longer than a blaster 1. ours cost 320 to do all up - including shaft purchase.. place at mt maunganui did it....think at the time gen yamaha was 800