Seat back or switch bad?
 

On my 84 300sd the seat back will not function with the controls on the door. If I push 1,2,or3 it will go to my wifes position. As she is 5'7 and I am 6'4 you can picture my problem. Does the switch go bad yet still work with the push buttons for the memory function.

For any problem MB switch of this era a good first step is a quick spray of electrical contact cleaner, as dirty grimy electrical contacts are very often the root of the problem. Good Luck!

Does the seat back operate when using memory? Then its likely a switch since the motor functions.