Just as a "d'oh" type question: Have you removed the spark plugs? You could be working against cylinder compression.
Barring something as simple as that, there have been reports that trying to roll in a new chain with the tensioner removed can leave enough slack in the chain to give a couple of problems. The chain can slip a cog on one of the gears, or the chain gets a 'kink' and binds up between parts down in the timing cover, especially if it was turned counterclockwise (opposite direction of normal rotation).
You might want to go over to the 107 forum on benzworld (dot) org (sometimes this site "eats" URL's to other sites), There have been a couple of guys that have had problems with timing chain replacement jobs there that could provide some help.
Just a couple of wild guesses from over the internet, take it for what that's worth.
Scott