i can likely help but it will be a long process.
if the drive shaft is siezed up you're going to have a chore getting at it, imo. it's likely sealed to prevent lube from getting into the food, a sealed for life setup. so that will need to be removed, taken apart, grease cleaned out, resealed with food safe lube, sealed, and reassembled.
if you have some pictures let me know.
also, these aren't generally super expensive, and restoring one wont be cheap. might be better to order new, or slice your meats by hand the old fashioned way. that machine if it was in a deli could have thousands of hours of operation, and everything could be straight up fucked.