I have a 1999 blazer. 4.3, auto, 4x4. due to a local mechanic dropping the trans pan and not putting it back on before going totally disappearing, for a year,I had to replace the trans and tcase. the shop put a used trans in, but it does not like to roll and it takes longer to shift than it should. should I take it back to the shop, or should I try to figure it out with yalls help?