Check what the posters have responded about, if nothing shows up then have a look at the starter itself, I’m kinda going off of assumptions here for this is what the mfd tractors sometimes would do also.  

a couple things the factory starter has a self resetting breaker in it, to keep somebody from grinding on the starter for extended period of time, that it appears to have a been somewhat troublesome.

the other thing is that there is a delay programmed into the starter circuit, I don’t know exactly what it is waiting or looking for but it can vary in length.  Tell him to hold the key in the start position for up to minute and see if it’ll start then.