With lawn tractor running, with or without blade engaged, the forward and reverse pedals seem stuck and will not move until I press several times on the clutch/brake pedal, alternating pressing on clutch and then forward or reverse pedal, until they finally release and engage--lurching either forward or reverse. Once engaged and moving forward or reverse, tractor continues moving at slow speed in the direction it is going even though I take my foot off the pedal. The only way to stop the forward or reverse motion is to press on the clutch/brake or to press hard on the forward or reverse pedal and allow to pop up. When engine is not running the forward and reverse pedals move freely. I've thoroughly blown-out all dirt where pedal forward-reverse linkage connects to the transmission and sprayed thoroughly with WD40, but the problem persists. Tractor was running great a week ago and this problem started while I was cutting our lawn. Thank you for any help offered.