I have a 86 420sel which seem to have a hesitation in the automatic transmission from first to second gear. It would hesitate to go into second gear especially when it is cold in the morning. When the car fully warms up, the transmission would work fine. I ask the mechanic on this topic and he said there is some kind of adjustment in the transmission to allow it to engage properly.

Does anyone know what this is and is this a DIY thing?

Thanks,
John