A4 Auto Gearbox

[lomond1909]

Can anyone help?
My auto gearbox exhibits all the symptoms of a low oil level, ie slow to take up drive and will not shift into top gear unless I do it manually.
There is no dip stick into the box, it appears to be a sealed unit.
How do I check the level and add oil?

[towcestervag]

a diag machine check temp and at 35-40 degrees a small trickle should run out of level plug the level plug is part of the drain plug centre part is like a small dipstick