The rod on the HF balancer is fine, so are the cones, I have one and used it on my last tire change.
Only issue on the balancer is you have to put it together square and plumb. Then make sure you place it on a good level surface.
The rod tends to move side to side a bit, the cure is to take the ends to a belt sander, and radius them int a slight ball end, then if they touch the outboard retainers the bar has zero friction.
Also, remove the rollers, clean them and lube them well with a light oil, reassemble and to not tighten them down like an ape.
Allign them so the rear rollers sit inside, and the front rollers sit outwards
Kinda like this
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There is absolutly nothing wrong with that balancer, or its parts, that learning how to assemble it and operate it won't fix.
The bar is the least of the worry. Any rod you get at home depot won't be an improvement, and I have never seen the problems you describe stephen.
The C14 axles are not 20mm the bearing sizes I believe are 17mm rear and 19 mm front, I just went out and measured mine, you can see the axles and measure them you know...... rear is slightly larger than 5/8's front is about 13/16's
I used a 5/8's threaded rod on my home made changer....
You have a C14 , go measure the axles .
