I am rebuilding a Marvel Schebler TSX-644 carb for my 1959 Massey Ferguson 85 tractor. I do not remember if I removed a economizer jet. I do not see one in my removed parts but the hole is there where the jet would be but I can not tell if a jet was threaded in the hole. I also cannot tell if the hole is threadded. I read that some early models have the eco hole but no jet. Is this the case with the TSX-644 carb or does anyone know what jet I need to buy if I need one for this model of carb. I also need to purchase a seat (1 inch small brass tube with 2 holes at bottom) that the adjustable main needle goes in. Where can I find this part. Thanks for any help. This is my first tractor and I am learning a lot about maintenance.