904 only works in PRND. No 1 & 2 fun.

No band adjustment. If it was you wouldn't have movement in Drive. Low and reverse use the same band and the intermediate band is applied for second gear.
In 1st the car doesn’t move from a stop and if you downshift to 1st the wheels lock up.
This is suspect that a valve is stuck maybe midway causing both bands being applied at the same time.
Again these are just thoughts.Diagnostics over the internet are tough.