The reason we don't want to remove the center 27mm bolt is that it requires approximately 240 ft-lb of torque to install correctly, whereas the 6 smaller bolts require much less, and are nowhere near as difficult to keep from spinning the engine when doing so.

I found that when I was working on my engine and replacing the front main seal, that there was enough dirt stuck around the nose of the crank inside the pulley, that it kept it from coming off easily. After cleaning out that area, things worked much easier, and it went back together with no issues.

That being said, when you actually do have to remove the main bolt, there is a tool designed to lock the flex plate starter gear, through the bottom of the bell housing.

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-Josh
Testing the cheap Mercedes axiom, one bolt at a time...