Hi Sheldon,
Congratulation for your Internet site.
I come from the electronic site but like to pedaling on my bike and like to know how to repair.
For that one have to learn. What I miss is start from Shimano and continue other manufacturer. This make more hard the works for other like yours who want help for others. One that there is not an indication table about all the main products
and what part you can change with what parts. The other thing that
I miss make even more difficult to find an equalent/same part that you can not have the measurements of the parts.
All the best.
Losi