My DR All-Terrain Field and Brush mower will not reverse. It has the Peerless 3628-P1 transmission. The four forward gears work fine, but when the reverse is engaged and the clutch is engaged nothing happens. The machine will not roll when in reverse, like it will in neutral, so I believe there's a problem in the reverse idler setup, like something is broken or locked up. But, the motor doesn't slow down or show any response when I engage the clutch, so who knows. Before I take the transmission apart, I'd like to know where I can get parts, or am I on the wrong track?