Dremel have a small diamond engraving tool shaped like a "T" - the flat top of the T is like a tiny grinding wheel. Perfect size to reach the post without touching the playfield...
With some care I was able to cut slots into the broken posts, and then unscrew them with a normal flat screwdriver.
Cheers
Jacob
Method I would be using, done this a few time before with success.
I would be careful drilling close to the existing broken screws. If the new thread bites into the broken screw then you will create more problems.
