[Rhodes22-list] Boom Car stop?

[PBR]

There have been many previous postings and photos on the dozens of different
outhaul setups but...I have done my time researching and I still have a
question.

My 89 seems to be set up like ravens' with the exception of the outhaul
passing through the boom.  The owners manual of this vintage offers that "An
adjustable stop in the boom track allows the car to be stopped at any
position along the boom....".  My boom car (sliding block) is locked in
place by what might be a allen head screw (kind of corroded and deformed).
I like the idea of adjusting this to shape the main when partially furled.
And now for the question(s).

Does anyone actually have a separate sliding "stop"?
Or was there supposed to be a thumb screw or something to quickly loosen and
slide the block?
If yes to either question, where can I get it?

Sorry no photo yet but hopefully someone knows what I'm talking about.
Attached Raven sketch.

Thanks
-Patrick
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