Hi. My Deere L100 runs rough lately, when it runs. I had an issue with the brake/clutch switch. It is poorly engineered not mounting well in the bracket. Only plastic strips are to be pulled away after installation. The idea is this is to hold the switch secure in the bracket. It may for a short time. After modifying & damaging the switch to get it to mount permanently I purchased a new one. The parts guy claimed to have no knowledge of the switches loosening & falling out! Strange when the internet complaints are there illustrating the same scenario. Upon installing the new switch I bolted it in. It is firm. No movement. Like the factory should have done. However, upon starting the engine ran rough. Puttering & spewing black & blue smoke while vibrating up a storm. So much for anti-vibration. I let it warm a few minutes & changed throttle settings. No change in erratic performance. I proceeded to mow. 5 minutes into mowing the engine stopped & wouldn't refire. I dried out the plug & decarboned it. Gap is good @ .030. Filters are clean. This tractor was purchased new in 2004 & maybe, read maybe, gets used 12 times a season on a 1/2 acre. I believe the engine is good. I think the switch may still be the issue despite being new. Please let me know what suggestions you may have. Thanks.