My 3095 dyna shift has developed a problem in the gearbox that is preventing it from driving. It has been been making a grinding noise when you let the clutch out after selecting reverse but sometimes it would go in no bother now the problem is it has lost drive altogether. I have checked the shear tubes in the back end and the are fine. I have also put a camera through into the gearbox and the selectors all seem to be there and moving when you move the gear sticks. Can anyone shed any light on what the problem could be?