The big pedal on the right side, not the forward or reverse pedals, is the parking brake. That parking brake pedal operates a safety interlock that prevents the PTO (electric clutch) from engaging the mower deck when set. More than likely there is an adjustment for the switch or the switch is failing. Sometimes a piece of debris, a twig or such, gets stuck up there. There is a possibility that the "new" clutch is defective or out of adjustment. Did you buy real JD parts or aftermarket? What was the original problem that necessitated the new clutch and switch and battery.?

I*f you can't "common sense" it by looking you'll need the technical manual for your X300 (and it costs $$$) or get your X300 to the JD dealer.

Thank you very much for your reply! I think we have narrowed it down to that switch. The battery was needed due to a very cold winter which froze the old one. The ignition switch was needed for much the same reason ..wore out. We went to the Reynolds John Deere dealer here locally to buy the parts so am fairly confident the clutch is ok. Will take a look at that switch. I know that there is no adjustment for the switch, and it is not dirty as it has been taken apart and cleaned. So either worn out or faulty is an option. The mower is 10 yrs old and never had a lot of work done to it so it is about time that things need replacement! Will let you know once we figure out the switch or replace. Many thanks!

Back To Normal!! It took a lot of trial, error, and changing different switches....but we have it! Under the dash, on the underside of the hours ticker, there is a switch. When this switch was replaced....all works as normal. I suppose the vibration of lifting up and sitting down on the seat, or pushing in the big pedal on the right and letting up, jarred that switch enough to get it to run. After replacing the seat switch, clutch, switch under the big pedal on the right, and cleaning all points, it is running like a Deere again!! Thank you!