The picture in the paper copy is not very good, and the pdf downloads images with lousy resolution, but I've attached a copy. If I figure out how to outfox it I'll replace it. In the meantime, the throttle sensor in all the models seems to be under the cover over the throttle and the FEL valve, and is bolted to the fender. A wire goes to the space behind the Intellipanel. Seems like the latter would be hard to take apart, but I haven't tried it.
If your tractor is still under warranty, I would recommend that you see if the dealer would send out a tech who may be able to id the problem and recalibrate using the Intellipanel in a few minutes. Worth a call to ask and could be an opportunity to learn something. I kind of hate the kind of interface you use to change settings through the Intellipanel, but that may be because I don't know what I'm doing usually and have to guess