Hi, I am not in the industry but use a Grashopper 721D front mount mower and am having problems. I am looking for help. Engine starts fine Blades turn fine when clutch is engaged Problem: The mower can no longer move forward. While both lever push forward, the right side doesn't engage with the transmission. I am a newbie and not a mower expert. So any feedback will need to be in layman's speak. Thanks in advance.