Originally Posted by Mitch's mom
Maybe it is reverse threaded. Try to turn the screw the opposite way - gently.
It took me a little to turn mine - I had to check my wiring and everything else. I know my shop didn't check mine and I'll never take a machine there again. I bought a machine from eBay and took it there to be checked - they were supposed to do a complete check up. They just changed a belt and light and told me the light switch was intermittent, and took 6 weeks. Never oiled it from what I could see or tried to fix the light problem. Charged $88 dollars - I just paid and took my machine and learned how to do things myself. Including removing the motor to repaint parts of the machine and redecal. Try taking the bottom off of your machine. (The oil pan) You will be able to see a lot of the wiring where it comes from the motor and light and then god out to attach to the plug. In fact you will see most of it. It's going to look crusty and oily, but wipe it off and see how it looks. Also - is the wiring from the motor to the plug free from cracks? And the plug itself and the foot pedal - any brittleness or cracks along the wire or where they attach? Check all the wires that can see and call the shop.