Treadle that Zigzags??
 

Tell us more about this. What model. What does it look like?

New? Janome makes their 712T machine. You have to use an existing treadle base for it, but it's a mechanical machine with ZZ and some other stitches too.
In the thread "Treadle sewing Machines???????" { http://www.quiltingboard.com/vintage...s-t193386.html } Charlee put in a link to the Janome machine.

~OR~

Snag any of the early Singer, Japanese or European ZZ machines that have hinges for the cabinet or box and a belt driven hand wheel and drop them into a treadle and take off.

My Alden with it's 30+ built in patterns and stitches is treadle compatible as is our 319K, 338, and 413 I think.

Lots of them out there.

Joe