hi can anyone help i've a 1991 fourtrack and when i push the 4 wheel drive button on the dash it lights up but front wheels not locking up the same happens if i put it in 4 wheel low but i read some one had the same problem so i,ve already checked the vacume pipes and all seems ok.But as i was driveing slow i pushed the 4 wheel drive button on the dash and it sounded like the drive wanted to engage so i stoped tryed it again and still the front won't engage any ideas. cheers