Last week I replied to a thread concerning doubles and stated that I did not like them due to the fact that in heavy grass they made my blade belt slip. I took them off and put on gators for my leaf cleanups. I noticed that after removing the doubles there was a slight bit of slippage when engaging the blades, other than that everything seemed o.k., Except for that smell. I thought It may be some leaf debris near the muffler or perhaps a little oil burning. Remember now, Ive been using these gators for a week and smelling that smell. I looked under the mower today and found the source of the smell. Somehow while changing blades the belt came off of the engine pulley and went up on the clutch area. Damndest thing Ive ever seen. This is why I was having slippage with the doubles. I still cant understand how it ran so long with the belt off of the engine pulley. I think I'll give the doubles one more try. p.s. mower is Exmark metro hp.