You would hope and expect that a transmission overhaul would be a once only operation?
To ensure that you do not have to tear down the transmission for a second time, ensure that you use new components with zero wear and zero damage. Even small items like washers and circlips are better being renewed. Interfacing new components with old worn or damaged parts may cause premature wear to those new (and probably quite expensive) parts.
This component and perhaps some of those listed below might end up in your shopping cart: