I was getting a bit of stretch on one of my home-made plastic tube couplings - the one for the Z-axis. I thought I should maybe upgrade to something better so I bought a few of these aluminium ones.

When they arrived and I opened the first packet I was disappointed. These things are much more flexible than they look. No stiffer than my plastic tubing couplings.

I dismantled the Z-platform and found a fair bit of dust and grease and swarf clogging the slides. A clean-up, a bit of fresh lubrication and some adjustments seemed to free the whole thing up. I decided to continue with the plastic tubing couplings for now.