ML270 Transmission Overrev

[lphot]

Can anyone tell me if I have a serious problem my engine revs from 2500rpm to 3000rpm when it changes from 3rd to 4th gear. It happens after the transmission warms up and after you go around a roundabout (chicane). It occasionally sticks in 1st gear when you accellorate hard or it kicks down to first gear. Thanks

 

[television]

A sticky valve maybe, but this could be low on fluid,hence going through a chicane sends the fluid to one side of the box

 

[lphot]

Is this minor or major repairs?
can you do it yourself ?
I have a 2002 model, electronic box.
Cheers