Hi i removed my auto gearbox and took it for re-threading because one of the bolts was loose ans used to fall out. When the gearbox was reinstalled all the gear selector lights on the dashbord were lit and it was stuck in D. Eventhough i change the gears to neutral or R. Selector still shows D

Please help

Hi i drive a 2000 golf mk4 automatic milage is 120000km, gear change from 2 to 3 is a bit rough. All other gears work well. What could be the problem? Do i need to change gear box oil?