Mine is the same way. Try to rock the tractor forward and reverse just a little with foot pedal as you disengage the front wheels this should make it much easier. there should be nothing wrong with your tractor as most 4wd trucks are the same way, hard to disengage the 4wd at a stand still. see page 25 of your owners manual. it states "to avoid damage to the transmission,when front wheel drive lever is not smoothly shifted, slightly step forward or rearward on speed control pedal."