There are several safety interlock switches, all of which must "make" before the starter will engage. These include parking brake (on), clutch (disengage), blades (raised and disengaged). You might have to check each with a meter.

Theres no switch that controls the blades ----the lever is attached to a cable that pulls the a pulley to tighten the belt to make blades turn --the switch attached to that is a safety if lever is engaged then unit wont start check and inspect that switch is mounted -set - and functioning correctly also have a fuse by battery -but check the other safety switches ---and the blades are a mechanical on -off