Lost power yesterday.. checked plugs, have to pick up new ones.. checked air cleaner, bad even though gauge doesn't show it...

Time to do a little maintainance..

Questions:

Air cleaner is fouled with oil / wet oil .. what causes that?

Gas tank seal (fuel line) leaks.. can that be just popped out and replaced w/ fuel in tank?

Anyone know of a Champion plug # for the Mule instead of NGK?