SL500 Trans Problem

I have an 1996 - Mercedes Benz 500SL that has a rebuilt transmission.

Trans type is MB722.6

The problem I'm having is that it slips very badly on hard acceleration and very occasionally on normal acceleration. This Trans was rebuilt and all solenoids were replaced along with the plastic circuit board that the solenoids attach to.

Any clues or suggestions would be greatly appreciated...

I had one rebuilt because it was slipping. After a few hundred miles it started slipping again. I took it back to the rebuilder and they adjusted something (modulator pump?) and blamed the slipping on normal break-in. It shifted fine thereafter.

Thanks for the quick reply. I'll have my builder adjust the modulator further to see if it improves the slipping.