I'm installing a Koenig type 51 PTO in my stock 1956 CJ5, for a front winch. PTO gear won't engage the transfer case gears when I try to shift it. Engine running or stopped, clutch in or out, forward or reverse. Won't go into gear, period. Anybody have suggestions? Winch is not mounted yet. The PTO lever moves and I can feel the gears rubbing, but they won't mesh. I've tried installing the lever both front-ways and back-ways. Shift operated okay on the bench. Both PTO and transfer operate fine independently, and are both in good low-mile condition. The PTO was opened and cleaned - chain and sprockets and bearings are unworn and are very stiff, but will turn. I done at least two such installs in past years but don't recall any such issue. What am I missing? Thanks.