My favourite printer is an HP Laserjet 6P. This wasn't the original Laserjet (I used one of those), but it's still pretty old. Noah didn't have one on his ark, but Moses used one to run off copies of the decalogue. Anyway, it's at least 20 years old, and I love it.
I love it because it's reliable, it's simple, and I can buy a litre of toner ink for £10 and fill up the cartridge, which then lasts for years. It can take a great wodge of paper in the tray so I'm not forever filling it up. It has *never* gone wrong or let me down, and every operating system known to humanity knows how to drive it.
But lately, the paper tray has been dificult to pull out for refills, and even more difficult to shoot back in.
Just now, I checked the level of paper; it was half empty, so I filled it, and when I did that, I thought, how about easing the slide? So I got a fingernailful of Vaseline and smeared it in the runner grooves on both sides, and now it slides in and out like it's on ball bearings.