Hello again!

I've had the gearbox overhauled and it runs fine again.
It had the following types of faults:
-worn clutch plates
-worn and twisted metal plates
-broken piston rings of the clutchpacks pressure control

All those parts, including oils & filter, cost me about 1000 euros (~1300$) so it was worth making.

Pressure of the packs rised 32psi to 152psi (10,5bar).

Luckily the oil pump and torque converter was ok.

Thank you all for your interest! This topic ends now.