My model is LZ26KC604, it's a 60", made in 2000 I believe. It seemed to run full throttle with no issues for a while. I recently replaced the air and fuel filters, spark plugs (properly gaped), installed a new battery, dumped sea-foam into the gas, and added premium gas. Later (a few more cuts) it basically went completely, and the mule belt shot off, and almost took my deck belt with it. I had my belts inspected before the season, and got the OK. I was able to start it a few days later and get it onto a trailer. I don't know for sure whether or not the interlock switches were looked at, but I am almost certain it is not electrical. The blades would start every time and run until the engine puttered out like it wasn't getting gas.