Have you tried shifting while rolling? Just barely push the handle until the hydro pump starts to whine, then hit the clutch and try shifting. I don't know if your machine has anything wrong with it, but from my experience all Axial Flows are hard to shift.
Check you linkage on the transmission. Its external and may be muddy or full of straw. Next, make sure the cables are all adjusted right. I had to put new gears in a 2188 last winter because the owner didn't adjust the cables and instead just used a tarp strap to hold the machine in 2nd gear. Gotta makes sure the gears are fully engaged and the detents are working right. If it comes down to taking it out, its not a lot of money to put the gears in (got mine from A and I through Worthington and it was under $800 I think.