The EHSS box is what controls the transmission on the DX55 more specificaly the shuttle shift. On my tractor when the left hand side panel is off the little black box has EHSS printed on it. Sorry I didn' explain it better. I ran it all day today without a problem. It could of been a seat problem. I wear my seat belt most of the time. When it was acting upI know I had it on. None the less I think the problem has been fixed. Renovator