i have an old john deere 316, and the blades have stopped engaging. it started off with the blades not coming back on if i accidentally tripped the safety switch in the seat, and now they wont come on at all. sometimes when i flip the switch to turn them on it tries to kill the motor like im not on the seat, and sometimes it does the same thing when i take it out of neutral. someone said it could be the blade clutch, or the switch in the seat, or the blade engage switch. any ideas?