Lulzbot mini 1 left z motor/coupling clicking

I dusted off my old Mini 1 to do some printing, and have noticed a problem with it. When homing and leveling, everything moves fine. While printing, the z motors flexible shaft coupling (most noticably the left one) will occasionally click and it jumps a bit.

I’ve checked all the connections on the board and cleaned the threaded rod. The couplings don’t appear to be cracked. There doesn’t seem to be any specific location that causes it or regular Interval it happens. Printing two 100mm test towers as two separate print jobs will show binding at different locations. On a 100mm tall tower, it appears to be losing around 7mm on average. is a link to the sound it makes and the visible jump in the coupling. It’s most noticable at the 22 second mark.

Any advice as to how to fix this? Thanks!

The answer was overheating. The rambo board fan plug was loose. I also took it out of its enclosure. It’s still weird that overheating only affected the z axis.