Classic/Antique Car Repair: powerglide tran leaks

Question
1957 belair w/powerglide transmission has been rebuilt and taken to 4 differnt shops 1 twice. when first starting out after setting.it won't shift, have to bring it up to shift speed, let off the gas and put into netural, then pull back into drive to get to shift. normally only have to do this once and then it will shift fine during the rest of the drive.
after the outting and putting it in the shop i have to place a pan under the transmission because after it sets usually for a few days or weeks it will leak out fluid depending how long it sets, may have to put 1-2 quarts in it before the next outing. the car is basiclly all stock w an original 283. it gets driven proablly around 1200 miles a year. any ideas??

Answer
I can't believe that the shops can't fix it. It is a very simple box.  You have to find the chevy club near you and ask them who knows how to fix it.  You have to find an old timer who knows.  It sure as hell should not leak.  I don't know anything about your chevy, but let me know if I can help.  jack