Originally Posted by
FBinNY
A video might help, but you're own eyes confirming whether the top loop sags when the wheel spins forward (coasting). This is pretty definitive, but note that I'm not taking about the cassette, but oiling the freehub ratchet or the seals between the freehub and hub.
BTW- some hubs and freehuns are very easily user serviced, others less so. Try searching for lubricate (brand/model) freehub and see what's involved for your specific model.
I only tried it once while riding. Realized the gears were messed up and the rest was just by lifting the back wheel and spinning the pedals around while shifting. Thanks for the advice though, I'll look into that.