It's an easy fix. It's rarely an issue if you're on top of making sure that piece stays level. Based on presses of similar design, It can come out of level and the base of the jack will slide slightly sideways. The two things are geometrically related. My experience with other s of similar style matches what the internet's collection of HFModders seems to find. I suspect that you've probably got to be doing something sketchy before that's an issue. That's exactly how it happened every time I did something sketchy. No incidents, but it obviously has to be corrected before you commence to pressing.....
I must also say that I've never had an "home" press act up. It's the light duty presses we use at work , which probably get asked a little much of some days...
Personal opinion. YMMV. I filled that "gap" in that cross piece with UHMW shims that I carved from a block that broke off of a sidewalk plow... The stuff slides good. It isn't really that much of a "stability" modification, but it helps a bunch with the rattling noise. Perhaps a lesser or non issue with the air jack, but using the manual jack, the rattle ate away at my nerves.
So yeah.... It's a thing that "could" help. I wouldn't call it "necessary". You'll know if it's an issue. If you have to straighten things before pressing, it's an issue. If you press while things are crooked.... You're probably not paying attention. "Fixing" this probably won't fix that, but leveling that cross piece and fixing your jack in place is a more solid fix than the shims are, in terms of forcing things to stay straight. Your call if it's warranted for your use case. According to Youtube, you could spend two lifetimes fixing all the things on that press that need fixing...
