i will try to make this quick.
i was driving one day and lost reverse gear.was told a ball had worn through a washer in the box and damaged the c clutch.ended up sending the box from ireland to england to be rebuilt.local bmw dealer refited it for me but since then when the car heats up the box starts to judder at 60ish mph. if i switch to sport it happens at about 70ish.it can also have a jerky change from second to third sometimes.i have had it back to the dealer but they could not fix it(they think the c clutch may be trying to engage).i am facing having to bring the whole car to england,any help would be appreciated,thanks.
g p.s.is it worth doing the tune up trick,is it each + to -?

SIXSPEED!SIXSPEED!SIXSPEED!SIXSPEED!

That's the correct answer.:stickoutt

sorry to hear about your gearbox woes, i have a high mile auto box so I fear I may end up in the same boat at some point. You see used gearboxes on ebay.de frequently, there's one there now http://cgi.ebay.de/Automatikgetriebe-BMW-E38-750i-E31-850i_W0QQitemZ270214414749QQihZ017QQcategoryZ61164 QQssPageNameZWDVWQQrdZ1QQcmdZViewItem.

It's done lots of miles (192k kms) and it's not cheap at €1200. I think you can do better, but it's an option.

Cheaper one, but with virtually no info..

http://cgi.ebay.de/Automatik-Getriebe-E32-750i-750iL-E31-850Ci-M70-BMW_W0QQitemZ230226574350QQihZ013QQcategoryZ61164Q QssPageNameZWDVWQQrdZ1QQcmdZViewItem

did you replace the torque converter?

As I understand it ZF makes a kit for repairing the swallowed plastic ball (No reverse). It involves only the valve body and no further damage is supposedly caused by the worn out ball.

This fix is only for the 840 and late 850 with the 5 speed autos. Lost reverse on the early 850 4 speed autos is something different.

thanks,but i think i will have to send the car to england and get the guy who did the gearbox work to sort it.