Confusing title, but in a nutshell, those experiencing slow to select gears first thing in the morning with their D2 etc will find this worth inspecting.

Serviced the trans on a D2a and noticed when removing the filter the customary second deluge of oil didn't occur. on further inspection noticed a section of the valve body seperator plate gasket sticking out, causing an air leak upstream from the oil pickup and allowing the oil to drain back from the converter and pump etc over time.

Dropped the valve body, split it (on the surgically clean steel bench), taking photos along the way as there are many little restrictors that MUST go back in the same way/ orientation on reassembly

New gasket installed (Genuine ZF only, some aftermarket ones arent well made, these need to be ACCURATE) reassembled valve body and back in the vehicle and all is well.

Other symptoms can be due to a damaged filter O ring, a leaking pump to main body gasket(shown up by external oil leaks too) and low oil level. It is adviseable to slightly overfill these gearboxes.

Hope this helps

JC