Yes, I have accessed it from behind with a hardened punch after removing the presser and needle bars, both from the access hole on the back side and from the side -- neither could get me straight on, so both at slight angles. It didn't budge. That's when I tried it from the front, and it only smooshed it flat. At no point was there enough to grab from either end. Hadn't considered a dremel -- enough power? -- but I am considering a power drill rather than the drill press.
I'm trying to visualize the clamp idea...food for thought! I'm in no hurry, want to take my best shot.
Thanks!