Well I got a S750 second hand, the throttle was cracked and when you turned on the power the thing would shoot off full power right away without even touching the throttle.
I thought I would try a new throttle for the mentioned reason and because it was cracked. The throttle connects to the controller through a six pin hook up. The six wires are gray, blue, red, black, and orange, the gray and orange wires connect to a circuit board with 4 LEDs the red, black, and blue I assume connected to the throttle part, (The damn thing came apart on me when I removed it). The only source for a new throttle seems to be http://www.monsterscooterparts.com/cutwgrth5pin.html but they are out of stock, any one know of any other places to get one?
You can get an OEM replacement here: http://www.thesuperkids.com/20ditwthwidi.html for a mere $60 plus shipping! Or, for about $8.50 plus shipping you can get your choice of thumb or full grip at TNC. That will have only the three wires you need for speed control and you will no longer use the other three wires coming out of the controller to the throttle. If you don't mind cutting and re-terminating some wires, it's a lot lower cost alternative.
Here's a pic of the 6 wires coming from my Stealth throttle and the three that are stripped are the ones I used to control the speed. I lost all LED's. Hope this helps.