Adjusting bed on older 1.5+ without eccentric nuts

I have an older (2016-ish) 1.5+ that I've been slowly tuning again after about 2 years of not being used (upgrading LCD, glass bed, etc). As I was double checking rigidity of all axis, I noticed the bed has a bit of play. Nothing crazy, but it could be better. All the manual refer to tightening the eccentric nuts and they exist everywhere except on the bed rollers. Any idea how to tighten these up and/or add them? The pic shows the outside of the rail with the two wheels, but the inside with the single wheel is identical.