Just to give this topic an update, I also experienced same prob, no WOT working and started as a rattle when engine running idle stopping for fueling, i had to be pulled by a truck home (yes it was a shame).
It left me several times in the street and then by magic It started, (Ive shaken it just beaause got nothing left to loose) and started by miracle.
That was till it definitely left me on the street and have to get pulled home. As I was being pulled, ive tried to start it in 3rd (nothing) so wasn't lo batt.
Sent it to Yam Dealership, good news, it was bad fuel (dirty) stuck in low tank which make me remember that ive used reserve very long one week later, so thats how dirt got into fuel pump.
They took out the gas, cleaned the tank completely and also cleaned the inner of the fuel pump (which has no fuel filter but inside of the pump a tea bag lookalike thing was stopping the dirt, so they put some injector cleaner for a night and voila now its clean).
Put it all back and started inmediately, no more hard start from now, and best of all, no yamaha reliability issues (really was very dissapointed bcause i thought with buying s10 i got rid of shitty servicing and reliability from my old KTM 640 adv, so started getting paranoid again::010::
Yes some may think getting something like a gas filter inside the tank somehow may fix the prob, the truth is taht this kind of prob is not so common but very annoying so what u might do best is to bring to service the S10 and ask every time to clean the tank (even if not dirty) and also check the tea bag of the fuel pump (clean it better).
Now im happy and confident it wont let me down again.
Saludos desde Chile ::021:: ::022::