If something is actually stuck, like redlineman said...you'll probably have to take the apron off. That's not a big job, but before you start taking things apart, make sure you have the half nuts disengaged. I'm thinking 820 also...which might not even be close, but if it is, I suppose it's possible that the the clutch could be gummed up and stuck. I've never seen that. Usually the opposite is the case. It slips when it's engaged. We really need a little more info to give you any real help with it.
Chuck