Thanks Allen,
I looked at your link, and I believe I tried all that, using a torx bit in a socket on a 1/4" ratchet. I probably didn't clean the torx head out well enough, but I still think the bigger problem I was having was that I couldn't sense when the torx was sitting square on the torx head, so it kept twisting out. It was much easier keeping the near torx square on. Pat's suggestion is probably best for now, for the torx bolt I may have damaged. I'll try using some Deep Creep or something like that to clean the heads of the remaining bolts to help ensure the torx bit fits more deeply into the head.
Larry
Edit:
I had a good look at the torx heads with a mirror and the ones nearest the frame were badly corroded. The T20 wouldn't fit into the head even after cleaning with Deep Creep and scraping with a tiny screwdriver. I read on some other forums to check the ground bolt first so I will check that out. I will also try Pat's suggestion because at the very least I want change out the bolts if at all possible.
I read somewhere that one guy managed to cut slots into the heads. I couldn't seem to get my dremel tool (with the snake attachment) to get close to the bolt. I fear that if I am not successful with Pat's method I'll be detaching lines and finding someone to bleed the ABS unit.
Larry