The best way to fix a Massey Ferguson 135 Tractor Steering Gear is to have the gear inspected by a professional mechanic or tractor specialist to make sure that the wear has not gone beyond its tolerances and to make sure that the gear is properly adjusted. If the wear has gone beyond tolerances, a new gear will need to be installed. It may be possible to find replacement parts for the Massey Ferguson 135 Steering Gear online or from a parts supplier. Additionally, many Massey Ferguson 135 Tractors are old enough that some parts may be available through a salvage yard or antique tractor club. It is important to use the correct parts to ensure that the tractor operates safely.