My guess is the slow response is from one or two areas- The vacuum pump/vacuum lines have a problem and/or the lock cylinder as mentioned above.
PLEASE dont twist the key in the lock hard or you will break the remaining portions of the U-shaped connector.
Feel free to email me if you have any questions.
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)