I drilled out the flap actuator bearing blocks to accept -3 bolts. I then match drilled the bearings to the skin. This went pretty well. The next step was mounting the platenuts for the four attachment bolts. This turned out to be a major pain. I tried usng the squeezer - too big. Then I tried using the pneumatic squeezer. It didn;t seem to have the power to compress the rivets. I had trouble getting either device back into the corner. I ended up drilling out half a dozen rivets (there are only 4 rivets involved in this step.)
I finally decided that pop rivets are great. The rivets only keep the platenut from turning, so they are not structural. I used the new pneumatic pop rivet gun to insert 4 flush pop rivets. Problem Solved!
I mounted up the weldament and quit for the night.