You have to consider metal hardness first off, if not soft or is too soft; heat hardening or work hardning metal, etc. etc.?.. i.e. how brittle is it cold? or hot? or after?
Clean clean clean before you start adheasives. Strong solvent, acetone, lacquer thinner, Xylene, etc.
You can knurl by squishing slightly with a hammer, squeezing in a big vice, or using a chisel- blunt or sharp depending on metal hardness and your best guess on reactions based on metal softness, etc.;
Ideally you want to make V-s with plowed up, raised, edges (splines), parallel to the axle.
Sometimes crossing the axis is needed or easiest, ect. though.
You can also swedge the end of rod/dowels with an X, and or center punch, or mushroom ends with hammers sometimes. Kinda like a rivet.
Vice grips sometimes have blunted knurled/cutting jawset, deep in the jaw. Grinding more of a V into that jawset might help.
Loc-tite has a new shockproof/flexing super glue gel out that needs some experimenting with, but may be promising.
They also seem to have a newer thread repair, I was under the impression it was thin, but I haven't looked into it.
Loc-tite high temp, high strength threadlocker, or better yet, loc-tite "bearing retainer"(hi-heat..green?) I'd expect to work better overall.
Hennings re-casts of some old wheels. Worth checking i.m.o.
I wonder if thin super glue, carefully applied into the cracks might stop the cracks from moving as fast; or if the capillary pull during cure would just flake or pull at other fissures?
A wetting agent/capillary/adheasion improver to get in to cracks deep? (I'll bet they have all of the above additives/pre-treatments at loc-tite's site.)
Cleaning wheel tread with acetone/nail polish remover asap of course, 
Once the deep fissures were filled, the outer "chunks" could be filled with JBWeld. ...I might try that with this once it actually starts derailing. What's funny is it's the only single reduction Marx I know of that doesn't need the wheels pulled to remove the armature. Triangular peak of one winding snakes pasts the break while the break is at wheels 10oclock, and "low"/gap between the arma.windings faces the good wheel's flange (armature gap at 8oclock on the arma&2o clock on the good wheel)
