I just experienced the stuck aluminum quill in my '79 Cannondale touring bike after buying a new head set to install. I tried every trick in the book here, including inverting the fork and soaking in penetrating oil (no luck), amonia (even less luck) and brute force (got it revolving slightly). I ended up cutting the top of the stem off leaving about 2 " at the top. The bolt hole was just big enough to get a hacksaw blade in. Had to hold on the a bare blade with gloves. After 45 minutes of sawing, breaking about 4 blades in the process, I was able to cut two channels into the stem on opposite sides. I used a flash light to check progress and to ensure I was not cutting into the stem, but aluminum is so much softer then steel that it was obvious when I was through. I use visegrips to squeeze down on the two halves and with some elbow greese extracted the stem. I felt like King Aurthur! Did not even scratch the surface inside the fork. Anyway, worth the effort since nobody has a replacement fork for a '79 Cannodale, with 27" wheels and brazed on brake studs. Good luck. Never say die.