Here are some pictures of my boats hardware.
Steve,
What may have happened is that the mast sheave may have got broken and the PO used a stainless steel bolt for the sheave axle which is perfectly acceptable.
You see,-- the sheave pins on the Z-Spar mast head and the Jib block are pressed into place and once you remove them, they don't stay in place that well.
All the extrusions on these masts were mfg in France and they were assembled in the states. Z-Diffusion was located in Bristol RI back then and they've since folded up.
I ran into the same problem with my Z-Spar mast when my pulley broke and I took my pulley down to D&R Marine and matched it up. Rudy told me that is was OK to use a stainless steel bolt as long as it isn't fully threaded. In fact I needed to insert a stainless steel bushing inside the pulley for the bolt to fit, as the hole was too large. I also had to drill out the hole in the mast head for the bolt to fit.
As far as the sail stop is concerned. A regular sail stop won't fit in the track feed on these masts. These type of sail stops are a pain in the butt anyway. A much easier, cheaper, and better solution is to use a short piece of 3/16" braid line of about 15" long. Tie the center of the braid with a strong twine to the top of your mast winch bracket and use a slipped reef knot to secure the last sail slide in the mast track.
When you reef your mainsail you'll need to untie this braid line and drop the last sail slide out of the mast track and retie the braid under the next sail slide. Then you can reef the sail. Dropping the sail slide out of the track will prevent it from binding. The sail slide can break with all the tension on it.
I'm not sure if the mast winch on the 192 Z-Spar mast is above the track feed like the O'Day 222. If you're not able to use the mast winch to support the sail stop line, you could always use a nylon wire tie and a screw to hold it in place. This also applies to anyone who has a mast without the winch and wants a great dependable sail stop.
Years ago I just used to untie the braid line and stick it in my teeth to hold it while I dropped the sail slide out of the mast. It's easier to just keep the braid line attached to the mast somehow.
Try this because I think that you'll find it a heck of a lot easier and faster than one of those knob type sail stops that you're more than likely to lose over the side anyway.