I am having alot of trouble selecting low- high gears! I have looked at the linkage and it was loose so I have tightened it all up but the Linkage seems to buckle with the force I am having to input to try and change from low-hi??? I have straightened all the linkage out and tried again but same, from high to low seems ok and diff lock works ok it's just low to high, I have now unattached all the linkage and have took the cover of top of transfer box were the leaver goes in and it looks ok? any ideas what to try next please