My B7100 hst was stuck in 4WD too. I'd just bought it used and it had been sitting awhile. I jacked it up so one side wheels, both front & back, were off the ground. Turned wheels by hand & jiggled 4WD lever; it came right out. I WD40'd the lever, cycled it a few times & haven't had trouble since. I hope it's that simple for you too. Best of luck!