According to my notes, checking the resistance across the coil of the ITPS reads about 2.7 meg ohms (not connected to anything). I know that sounds high, and some cheap DVMs won't even read that high of a resistance measurement, but that is what I have in my notes. I will check it again tomorrow, I have new one over at my shop, and let you know if I made a mistake. Another way to test it is to simply check the voltages at its contacts as you move the core from its resting position to full throttle. One contact will show between 12 and 15 volts (the supply energy to the ITPS) and the other should vary from about .5 volts (slow speed ) to 1.5 volts (fast speed ).
I went ahead and remeasured the new ITPS that I had at the shop with a DMM on ohms, and this time I got an even higher resistance (about 3 meg). But testing the DC resistance is only a way to confirm that the ITPS isn't "open". It consists of MANY windings of very fine wire, and generally is either good or not (shows some DC resistance or not). I've only had one, in all of these years, that showed DC resistance and didn't work. It offers its impedance to the circuit (to set the level of its output) through Inductance (not DC resistance). The voltage testing is certainly a more reliable way to see what is going on with it. Many times, I have thought I have thought that I was experiencing ITPS issues only to find that it was a problem with its connection to the Motor Speed Controller. You can trace it out from the throttle box all the way to the MSC. There is a jack and plug along the way that is notorious for creating the open circuit. Good luck!