Tecumseh 8 hp TVM 195 runs but will only start with starter fluid.

Hello, can anybody help me. I have a old Snapper 8 hp 4-cycle Tecumseh rear engine mower, the number on the motor is TVM 195, the problem I am having is it will not start on it own I have to use a little shot of starter fluid for it to start, once it starts it will run until I turn it off. I have rebuilt the carburetor it is a series 3 carburetor, I am not sure if I have the linkages connected correctly but I think I do because it runs, it has a governor and a governor override, there was nothing connected to the choke and when I look in all the manuals they show nothing connected to the choke and when I asked at the Snapper service center at Ace they said the choke works automatically with the vacuum of the motor. Once I spray the starter fluid in the breather it will start on the first pull and even if I turn it off and I then try to restart, it will restart without the starter fluid on the first pull. I have rebuilt the carburetor, put in a new spark plug, installed new fuel lines, put in a new fuel filter, put in a new air filter and changed the oil. While the motor is running I have tried to adjust the main mixture screw but I can't notice any difference I can unscrew it until the gas starts coming out and if I screw it in all the way the motor dies and when I try to adjust the idle mixture screw nothing happens. Thanks for any help.