Mini 1.0 missing Z steps

I’ve been working on reviving a Lulzbot mini 1.0 that was donated to our makerspace back in 2015. It had a long list of things wrong with it and I finally got it printing again. For the most part, everything seems to be working okay. However, I’ve noticed that the printer occassionally misses some z steps. When moving z axis, it occassionally misses some steps, resulting in non-smooth motion. I suspect this is why some of the layers whilst printing end up getting squishes together.
Here’s a video of what I mean

Any tips on how to resolve this?

Just in case it’s useful for anyone - I believe the issue was stepper driver overheating. The drivers had no heatsinks on them. After adding heatsinks, I’ve done over 100 hours of printing now with no issues


Take caution as you could damage your 3D printer if your heat sink falls off.

Our internal testing has determined that the heat sink provides no added benefits. Your 3D printer will
operate normally without this installed.

If you are having issues with the stepper drivers overheating, I would check that your case fan is functioning.