Automatic transmission Caravan 1992 3.0lt

Hello good night, hopefully they could help me, 15 days ago I took my truck to change the crawling oil retain because it already threw a lot of oil and logically tubed to lower the velocity box and now the mechanic cannot ride it, every time it is mounted, the crank and loosen the screws of the box a little and the crankshaft already dull? Etara putting the turbine badly? Or lake that swims badly, I need to know why it is my work tool and it is a lot of money I hope to have your support thanks