Got a free mower with broken push bar. Craftsman 917376741. Battery is gone but starter is still there. I unhooked the starter wiring so I could use a 12v power source. Starter cranks fine but no spark at plug. I see there is a interlock switch next to blade brake lever. Is this switch to ensure starter cannot be cranked with brake on? Former owner said mower worked fine. Hmm, bad coil?