I have a Grasshopper 721D that shuts-off the fuel solenoid after a few seconds of running. I have checked the parking brake switch, left & right steering switches and the seat switch and all test OK. The PTO switch was replaced about 2 years ago, however from what I've read the safety interlock module (184220) is most likely at fault. I hate spending the $50 for a replacement without being certain first. Is there a test procedure I can go through to confirm the problem? Any help would be greatly appreciated, as my leaves are really starting to pile-up!