i'd like to help you more bz, hopefully there are some here who can....my exp. is w/ late model CATs and joysticks... new CATs also have a decelarator (it serves like a brake really).
IIRC, it (decelarator) needs to be pressed down all the way to start the machine....at least for CATs......new safety stuff, and you release it to get going.
My comment based on my experiences, is to keep the machine geared to minimize use of the decelarator...i.e. your leg will get wore out if you use it to slow down or stop all the time. try to maintain a consistent gearing so your speed and torque matches what you're doing (i.e. slow ripping, fast ripping, shallow scraping, deep scraping, pushing small or large bladefulls) and try to keep from using it all the time...i found it useful on steep hills more as an emergency slow or stop if i was starting to get into a little trouble, but on gentle slopes or flats was really only using at the end of a push or a rip to change directions, turn around....
good point by H2O, when i was carving holes in pond sides (cliffs), the decelarator aided alot in doing more precise digging.
