Thanks to the help from this forum, I installed a Chinese sprag combined with a Dyno Dave starter plus cables, and my bike has started on the button every time, over the last few months.
The mating surfaces for the contact area of the sprag had minor signs of wear, but I figure that the price of the occasional sprag is worth seeing how it goes, versus the replacing more expensive items. So far has been going very well and I appreciate the info about the alternative. I will probably get another to have on the shelf, should this one eventually fail.