Kwik-way vs valve grinder

I am new to this form and my first post. I acquired a old (green)kwik way VS valve grinder that was sitting in the back of a friends new shop when he moved in, its been sitting for along time. I got all the crud cleaned off and it has a problem that allows the slide comes off the fork when indexing to the valve stem grinding side (right side). I bought a old manual and found the stop screw that should limit the slide on the right back corner of the grinder but nothing for it to hit to stop the slide. Its obviously been apart before and missing some pieces, Would anyone out there have one of these that could look and see what the stop screw should be hitting to stop, there is nothing obvious like bolt holes for a stop tab or any thing broke off. thanks in advance.

I had a Quick Way many years ago. But I must say, nothing like a Sioux to get the job done.

here is a range of grinders https://cvomachinery.com.au/valve-grinding-equipment.html#!vg28_01

you may find a modern one will outperform a older one, with exceptions. I don't like Italian machines i generally think they scrimp on the quality aspect, so see what they do then look elsewhere.
The warren and brown used to be good.
Surely there is a better one out there.
Look into the sioux as well.

here rottler Rottler VR12
Valve Refacing Machine with Centerless Grinding