Thanks, all! This is very helpful.
I'll try to post a picture this weekend, though it's all under a tarp now. There is a hole, or recessed tube just forward of where the crank attaches for the outhaul (near the gooseneck on starboard). It hadn't occurred to me that there might be a button down in there. I did try to see if a screwdriver caught anything.
I'll also check the bottom of the boom but don't recall seeing anything there.
Sounds like Brad's boat and mine are very similar and that sailonct has the original boom. I've still got the track for the traveller between the cockpit and lazerette.