I'm away from my bike until next week, so I can't post a pic until then.
I had a handle from an old wheelbarrow, I think it worked well because it is hardwood and could be torqued without cracking. One end is square, where it was attached to the barrow, the other is tapered and smooth where you would grab it. I lay the square end on the retainer ring, and marked the position of the indented round holes, then I drilled it out on those marks and inserted stove bolts that were the proper diameter and length for the retainer ring holes. I bolted the stove bolts onto the wheel barrow handle and viola...sorta. I had to work pretty slowly. That retaining ring was really frozen in there, and I think I remember using a cut-off screwdriver, and liquid wrench, to help get the whole process started. Hope that is some help.