I have a Scag Tiger Cub Model STC. I purchased in 2004 and it has 1,515 hours on it. The motor works fine and drives as usual. Today when mowing the blades just quit mowing. The belt is fine and appears to be properly aligned. My first thought it was electrical. Being 12 volt system I cleaned all of the grounds. I cleaned the contact points in the PTO switch and the plug going to the PTO clutch GT3.5. I am now at a stand still. Should I Look towards replacing the PTO clutch or the interlock module? I seek your wise counsel. Thanks!