Once you have the Impezza oil plug it bacomes very obvious it is much too short to work as the puller. Maybe the reason for the M10? I just stacked 10mm washers, used my cordless impact, and it came right off no struggles.
Here's a photo... also show are a worn starter clutch spring, and a new one. About a 1/4" shorter for the worn ones. When it got hot it sounded like a bunch of marbles shaking in a coffee can when I tried to use the starter...