A couple of months ago the pull up knob to engage the blades broke. I picked up another and swapped it out in no time. No problem. The dealer told me to look at the connectors to make sure they weren't shorting and if so how to fix it. I looked and they where fine. Well every once in a while the blades don't engage when I pull up on the knob. It really only happens once every couple of days. But now that I'm getting up leaves and I'm dis-engaging and engaging so often it happens more. I just keep pushing and pulling the knob until they engage. I've checked the connectors again and they're ok. Any ideas on anything else to check? Possibly a bad switch? Any ideas anybody has would be great.