trans leaking again after rebuild

When I do a transmission, after I put in the new bushings in the pump, I'll stick the pump on a convertor to make sur it spins freely. Bushings are like cam bearings and can get tweaked on install. It's nice to verify it before it's all together. It sounds to me like a bad pump seal, especially given the issues getting the convertor in. Stuff out the vent is usually a higher rpm thing, and the gasket around the pump and kickdown level plug don't usually leak.
In terms of time - I could see a repair going 4hrs. A rebuild would go longer unless the guy didn't measure much, or didn't replace the bushings, or both. My best start with a complete and grungy unit to finish has been about 8hrs if I can use someones jetwash and blasting cabinet.