I'm working on a 7420 with a powerquad with left hand reverser that will not move forward or reverse. The code is epc 306040.31 which I believe is "not-neutral switch closed by mistake." I figure this means the wiring to the neutral switch or the switch itself is bad. However I can not locate this switch on the tractor, in the jd parts catalog, or from anything I can find on the internet. What switch am I looking for and where is it located? Any help from the experienced people here will be much appreciated.