I've replaced pads on two of my Benzes. I used a putty knife to remove the old pads. I removed as much as I could and didn't worry about the old adhesive. I used 3M contact cement on both the pads I replaced and have had no problems yet. The first pad I did was 4 years ago.
I bought a cheap 97 cent brush top spread the goop over both the hood and the pad let dry. Yes, you only get one try at lining up the pad. Do a dry fit first to see how the pad fits and how much may or may not get tucked into the front or back of the hood. Mark the centers with tape and start with the front or back, then stretch the pad to the other end and press it into place along the center, then work your way to the outsides.
'05 E320 CDI - 86,000 miles
'86 300SDL - 360,000 miles
'85 300SD - 150,000 miles (sold)
'89 190D - 120,000 miles (sold)
'85 300SD - 317,000 miles (sold)
'98 ML320 - 270,000 miles (sold)
'75 300D - 170,000 miles (sold)
'83 Harley Davidson FLTC (Broken again) :-(
'61 Plymouth Valiant - 60k mikes
2004 Papillon (Oliver)
2005 Tzitzu (Griffon)
2009 Welsh Corgi (Buba)