Just to recap on a recent inquiry of mine re. what I thought was gear-change hunt at abt. 55mph. up a slight incline, from this website I have learned the following --
The regular in--out, in--out effect shown on the revcounter accompanied by the same regular slight brrr--brrr noise is in fact the torque converter's clutch being actuated regularly by the transmission control module, but for spurious reason. The clutch is not used on lower gears, so the effect can only show on higher gears, esp. 6th. I noticed that the "hunting" could be immediately stopped by lifting the foot off the gas pedal by only half inch or so, not even enough to slow the car.
This effect is 'learned' by the TCM from the driver's style of driving, i.e. adaptive shifting. The effect can be stopped by a reset of the TCM, but will come back again as the TCM re-learns the driver's style. This has worked out in practice, as before I got the car, the battery had been disconnected to try and cure another prob., the jammed park-brake syndrome.
The following remedies were advised:---
1) Replace the torque converter & clutch. Astronomically expensive.
2) Replace the transmission fluid. Also quite expensive for special german ZF fluid. Also not a simple job. Fluid has to be exactly right quantity. Also opinion has it that this stuff is not a sealed-for-life affair, some contributors said fluid replacement cured the hunt. My car has done 120,000miles.
3) Add a german additive supplied by ZF which modifies the friction characteristics of the fluid.

I would VERY MUCH appreciate advices on fluid changing, and additives esp. in terms of cost from senior members who have sorted this prob. in real life.
I also get now and again what has been called the "cattle-grid" effect or "wasboard" effect, I thought that was a suspension or peculiar road surface effect, but realize it could also be to do with torque converter/gearbox.
I looked at a website with a very similar name to this one, and it seemed really inferior, full of flaming and aggro., so I'm staying here!
I can live with this transmission I suppose if it's going to cost an arm & leg to fix.
Thanks in anticipation, Leedsman.

 

Note:
1. A battery disconnect does NOT clear the adaptions learned by the TCM. You need a dealer tool to do that.
2. If they are cleared, the TCM will NOT necessarily relearn in the same way.
3. You may not have the current TCM & PCM calibrations.

A battery disconnect only clears the PCMs learning such as fuel trims. No help at all with this.