Well, personally, I'd contact the company who made it and ask them.

I have zero experience with printers using threaded rods for anything other than the z-axis - and had no problem with those.
I'm now pretty much a total delta convert - belts all the way :-)

Just thought that pattern definitely looked like an interference pattern - which you would get with threads being slightly out of sync.
How you would fix that - not a clue. sorry.