There is no crank position sensor, only the Cam positions sensor, which does essentially act as a crank position sensor. Problems with this sensor are fairly rare, but you see them every now and then. Some issues have been tracked to the position of the sensor, since there has to be a certain distance between the sensor and the crank for it to work properly. About 50% of the time replacing or repositioning the sensor fixes the problem and the other 50% end up being hard to track down. I have seen a faulty ECU be the cause of this and also a faulty wiring harness.
The magnetic part on the crank that the sensor "senses" could be a problem (maybe coming loose or turning on the crank???), but I've never seen that as the fault.
If the ski is running good, I don't know whether I'd be inclined to mess with it at this point, because just about all options from this point get pretty expensive. Its my understanding that the ECU pretty much sets the timing and the Cam sensor is a way to fine tune the timing, so in many cases the ski may run OK without it...........just not optimally.
2008 Yamaha FX HO Cruiser
2010 Hurricane Sundeck 2100