I did weld nuts on and finally got them out. I used a combo of propane torch heat on the aluminum, ATF/ Acetone, and working the bolt back and forth. I could only get about 1/4 turn on them at first, but just kept working them until they finally started to rotate further. Now Its time for final cleanup and then assembly.Have an electric welder? If you do, put some appropriate sized nuts on the broken bolts, and weld them on. The heat from the welder will convince the bolts it's time to come out. Let the welds cool for a bit, then should come right loose with a wrench or socket.