i have a 300 xpress that I have owned for about 2 years. In this short time I have rebuilt the motor top end-braking system-starter-Installed new chain and sprockets and a new battery. And now I have transmission trouble I thought it was the shifter box because it would not hold in reverse no matter where the adjustment was. But a few weeks ago when i went to shift from hi to low it jammed up and would not shift into any gear. So I took of the shifter box and went all through it and cleaned it up and put in new oil and it works good with the linkage unhooked. But when i hook up the linkage sometimes it works in the forward gears and sometimes it does not. When I try to shift it will not go into gear it feels like the handle will not move frontwards or back. Has anyone ever had this problem. If anyone knows how to fix it and lives anywhere around Louisville KY let me know i will pay. Thanks alot for any help it has been a long and hard road with this quad.