Bronze Huge Axle recipe: is using two long rods like the medium axle, instead of following the paired quadruple ingot pattern of the other four metal tiers.
Wooden Huge Axle: does not have decomposition material value (8 x U Treated Wood). A minor oversight in what is likely manual but boring and obvious [recipe scanning uses of creosote + wood for material composition tags could slow loading].
I could find no method for re-starting a jammed gearbox. Removing the offending gears or axles connected to attempted extra power input left it siezed until broken and replaced (quite an effort with having to also break and replace the axles for gear face access). Logical suggestion: make it reset with the Soft Hammer (wood/rubber mallet) like most other machine that can get stuck.