you could try twoforks suggestion with the wheel off, just the drum on and the axle bolts to the drum.
I usually find that about a 6 foot fence post or a 6 foot 2x4, used to pry, alternating top and bottom of the drive tire, with the mast and/or carriage as fulcrum, sort of "walk" the tire and drum (with the axle and bearings out), is about the only chance your gonna have. Sometimes CAREFULLY setting SOME of the truck's own weight back on the wheel will also free it from a 'cockeyed jam'.
hazard warning;
I know that I/you can break a 6 foot wooden 2x4, or bend the fence post like this, (fence post not being the hardest metal pipe you might find, but is light enough to handle without spending too much effort just holding up 6 feet of pipe and about the right diameter to allow access between the mast and wheel) but if I/you put that much grief on the 2x4 and get no motion before it cracks, it is time to try to find some leverage at a different spot. if it moves at all, then it is time to get a different bite at a different angle of/on the drum.