I have a 1985 190E with power seats and headrests. The headrests will no longer go up and down, yet I can hear the motor working when moving the switch. I am thinking they be frozen after not being used for so many years. Any ideas on how to get the working again? I would appreciate any input. Thanks, Joe

Here is a link to a previous post regarding your problem. I used it to repair mine. This is for a W124, but it should help.

W124 Power Headrest Fix...Easy DIY!