They ARE terrible, if that moped still has one, that is probably where the leak is coming from. Being that old, it is highly unlikely it still has one, the cheesy fish tank lines rot and turn to dust in less time than that. I'd mostly be concerned about the shudder. Could be the clutch lining (you have to replace both complete clutches if they are bad, and they aren't that cheap), could be low or overfull of oil, or it could be something worse, like a bent or worn shaft or a bad bearing. But I'd bet on the clutch lining. You would have to tear it down to find out for sure, unless just changing the fluid fixes it. And yes, Mr. Targaped, I have has Tomos engines and transmissions COMPLETELY apart before, and put them back together, and they ran great. What do you think about that, huh?