I have refitted one and totally replaced another. I had the worn one tig welded and smoked the fit with files and stones. Just be patient. I made a new one to replace a missing bolt out of drill rod if memory serves. They are slightly tapered and I left them a bit proud of the fence to wear in. If you are used to fitting parts by hand it is not hard, just tedious.
If the top lever spring is weak, buy or make a new one.
Tedious is what I am assuming, and have Swiss files and stones ready. Seems pretty straightforward, but looking for hints. Confirmation is good, too. It can only lock one way...
