The cheapest thing you can do at this point in time is to flush it. The problem with that is unless it is power flushed the
torqueconverterwill remain full of cruddytransmissionfluid. Yes you can do it your self, it is generally messy as you need to jack the thing up and unbolt thetransmissionpan unless there is a drain on it some where and the drain the fluid, the unbolting of the pan spills it all over the place. You will need a new gasket and some gasket sealer, RTV or something better. Your choice. It probably would be to your benefit to try to take the warpage out of pan hold downs with a hammer, actually two, one to hammer the point where the bolts went through if that is how you had to deal with things things and the other to act as a dolly. A new filter because it never hurts to have one and what ever
transmissionfluid is required.
And my suggestion would be to obtain some LUCAS
transmissionadditive. I have had some interesting success with Lucas products to the point now when I perform atransmission
maintenanceI automatically use it.