There should be a short peg inside the bore of the headstock that mates with the groove in the side of the collet. The peg keeps the collet from turning, allowing the drawbar to be tightened (never tighten more than finger tight or you will damage the collet). If I'm reding your question correctly, it's possible that the peg was, for some unknown reason, ground off or removed. The peg should be relatively easy to replace if it actually is missing or ground down.
Sorry, I misunderstood what was spinning. I'm somewhat surprised that the epoxy didn't work.
Something that might be possible if the handle isn't cracked is raising enough of a bur on the center piece that the handle has enough purchase to hold, which may be difficult (the steel could be hardened). Other things you could try are a different type of glue, drilling and pinning the handle, making a new handle, or (the for the most work) boring out the handle and making an insert to fit with a friction fit.
Of course finding a drawbar for a Boley lathe probably wouldn't be impossible, and there is also fabricating one from scratch.
Ahhh, JB Weld? Pretty amazing stuff. Most hardware and automotive stores have the stuff. I find myself digging it out all the time.
I just recently bought a lathe off e-bay, and when I got it in the internal ceramic matrix in the foot controller was broken. Anyway, with a little JB Weld I “welded” to two parts back together and it works perfect now.
I think every shop should have some of the stuff. If you try JB just give it plenty of time to set up. The longer it cures the harder it gets.