when i switch into 4wd the machine is fine,when i disengage the left front hub locks,which makes the machine pull hard to the left,i have to back up and it disengages,any ideas on what might be happening?

 

change the fluid or better yet take it apart and clean it then change fluid

 

Most likely armature plate in hub magnetized causing 4 wheel drive on that wheel.If this is the cause REPLACE both sides as other side will eventually do the same thing! Plates are about 10 bucks each. I do this constantly on the older machines as they wear and get a few years on em! One reason I think they went to centralized awd system Also check for seal leakage/low fluid level. May can get to operate by just cleaning and new fluid as mentioned above! Good luck