Ok guys Im stumped. I had my 47RE rebuilt by my friends mechanic when the the overdrive exploded and nowafter the rebuild it slips from first to second gear. Any suggestions where he went wrong? It has a Sun Coast valve body in it but I have no clue if he cleaned it out. Any suggestions where to begin??

 

Possibly start by checking the bands. Any slippage from 1st - 2nd usually is from the bands being loose/not properly adjusted.