TB42S Auto - Lock-up Shudder

Hi,

Last year I reconditioned my auto gearbox (RE4R03A) which I posted about here. All has been going well for 10,000km or so. Been using a manual Torque Converter lock-up mod since christmas with nice results.

However, after my last trip (CSR) I noticed during the limp back home to Perth that the torque converter was occasionally shuddering. It feels like driving over a cattle grid and seems to last a couple of seconds before going away again. This doesn't happen during lock-up itself but some time after and not consistently either. When I got back I dropped the fluid and it looked a bit brown but didn't smell burnt like it was when I rebuilt the box. I suspect the oil is passed its best which is surprising after only 10,000km, but then again, I did just give it a hammering for the last 6,000km, mostly off road. Last year I used OEM oil that I bought from Driveline AP in Perth. This time I refilled with some fully synthetic ATF (Valvoline Max-Life) and ran for a few minutes before repeating to get mostly fresh oil into the box. At the same time I fitted a transmission oil cooler to try and slow down the oxidation of this new batch of fluid.

On driving after warming up the shudder in lock-up came back. Happens occasionally in 2nd, 3rd and 4th and stops as soon as you turn off the manual lock-up. So the problem is still there with a vengeance! So I have a few questions for those that have also had auto woes:

-How long shall I run around with shudder to see if the new fluid makes the shudder go away?
-Can I really have stuffed the torque converter clutch in 10,000km?
-Could it be low line pressure?
-Could it be a knackered line pressure or torque converter lock-up solenoid?
-Could it be the input shaft seal?
-Any other ideas?!?!?

Cheers,

Sam

Yep, I replaced the TC during the rebuild. I did the rebuild myself so I guess it is take apart time again. Oh well!