Lucas J. Pretty tough looking little fella. I love those tires. It makes the tractor look like it is ready for some serious work duty.
Rich Trevaine. Donald Tanner made some good suggestions. Let's take things a few more steps further. I am somewhat a "lazy" details (the more information that is provided the better that we can assist the customer) person so forgive me if I ask a few questions.
You say that tractor won't go forward when you move the lever. Do you mean it will go backwards/reverse if the lever is moved to that position? .... If so then you have a sticking check valve. If that is the case the remove the tunnel cover and MARK just one of the check valves. Now switch both valves and if the tractor now moves forward and not backward then you need to either try cleaning or replacing the sticking check valve.
Next question.... Did you re-install the charge pump cover to the correect orientation? If not you are not gettng enough charge pressure to the rest of the system. (One should ALWAYS mark the side of the charge pump cover and the corresponding pump housing part to help achieve correct orientation during reassembly.)
When priming a pump, I suggest removing at least one of the check valves and using a clean funnel then keep pouring oil slowly into the open hole while every so often hand rotating the pump. This helps get oil to other parts of the system. Don't ask me how much oil it will take. Just use common sense and go from there. You want to fill as much of the pump and motor areas and other parts of the pump as possible and help bleed out any air in the system.
DON'T run the engine while doing this. It is a by hand operation only. Slow ... yes.... worth it? DEFINITELY!!!
As Donald T. said.... Make sure the rearend is filled to the correct level. If it already is then the little extra oil that you are adding during the priming process won't hurt.
PLEASE KEEP US POSTED ON YOUR PROGRESS.
Now... A little footnote about being a "DETAILS" person. Whenever taking on a project for the first time. Go slow and take time to literally study, photograph/take pictures, and be PATIENT during the whole process. By doing so you will tend to avoid common mistakes. When I tell people to actually talk to the object in a calm manner and "ask the item" what is it that (You)/I am not seeing then in a sense I am doing what a doctor would do and that is ask the patient to tell me where it hurts a.k.a. ... what am I not doing correctly. This boils down to one word.... FOCUS.
Last month while on a Road Trip to Oskaloosa, this little fella caught my eye. He'll be coming home by next spring at the latest.