Originally Posted by DanielFD
I updated my cars software with ISTA/D. Seanjordan is right too, this doesn't always solve the issue. Solenoids most probably will though. But having said that nothing is truly a sure thing with the ZF trans, or with any transmission for that matter. So many different parts can contribute to the same symptoms. Problem solving a transmission without breaking your bank is very much a hit and go thing. Though its a general agreement that the valve body is the weakest link in the ZF. Solenoids is the usual first fix before refurbishing the valvebody itself, though it some cases it would have been cheaper to just re-manufacture the valvebody while its out. So it all depends on how much you're willing to pay and how much time your willing to put into the issue.
In the ever-popular "So you bought an e60" document -- they have a special section where they talk about troubleshooting transmission issues.
In order (and probably by $ amount as well) -- this should be the procedure: (1) new fluid and filter; (2) reprogramming; (3) new actuators; (4) new mechatronics (or solenoids) or (5) new transmission.