So currently my 2006 JCB 214 3C appears to be stuck in four wheel drive. all 4 wheels in the air, foot heavily on brake, I engage drive from neutral. I see the front wheels jerk. Slowly let off the brake and all 4 wheels start spinning. This is with the 4wd switch not engaged(I’m still troubleshooting this issue) but in the mean time, Can someone explain to me why I had to feather the brakes to get the four-wheel-drive to actually lock in when I was coming out of a super steep ditch the other day?