Rebuilding the carburetor on a Massey Ferguson 135 is a major undertaking. Begin by identifying the carburetor model; there are several variations used in this tractor. The MF 35 and MF 50 are different. You will need to choose the proper rebuild kit for your model. Make sure to thoroughly clean the carburetor and all components in a pan of carburetor cleaner before disassembling. After the carburetor is disassembled, inspect each part closely and replace any worn parts, such as the shaft, gaskets, o-rings, etc., included in the rebuild kit. Reassemble the carburetor and make sure all parts are properly tightened before reinstalling it on the tractor. After the carburetor is installed, reinstall the fuel line, fuel filter, and air filter, and then adjust the idle screws, if necessary.