I'm inclined to agree with this one.The connecting arm of my G1 Sinnertwin snapped on me so I just pieced it back together with superglue (and he's now only ever Abominus' leg). So far so good. Since you're talking about a developed crack rather than complete breakage then I think the superglue method should work well. Also because Tracks' legs don't really have articulation anyway so you're not going to place any physical stress on it by making the leg or knee bend.
Although if you do want to grab a loose incomplete Tracks to salvage for parts or just use as an outright replacement for your reissue Tracks (just keep the accessories), one just sold on eBay AU a few days ago for $17.