On my 190e 2.6, I got seal press kit from Harbor Freight (Check their web site). The kit is nothing but a set of round plastic pieces (different diameters for different seal sizes) with a hole in the middle. Like the Chips in a Casino. Sandwich the seal between two pieces out the kit, then stick a long bolt throught the whole thing and tighten the nut. The seal will press in the hole as you tighten the nut. This will provide even pressure around the seal. You can fabricate your own tools. You may try big and flat washers. When removing the old seal DO NOT SCRATCH THE SEALING SURFACE. I use loctite 5999 to seal the cover. The MB sealant is Loctite 5990. Both are pretty much the same. I ordered a 300 ml tube where I work from a usual supplier. Any other good quality sealant may work. I personally prefer Loctite products. Visit their web site (
www.loctite.com)
Note. You may need to carfully work the seal around the camshaft with a small screwdriver as you put the cover back. I had to do this several times until I got it right.