TAZ6 reliability

Hi,

I purchased a TAZ6 about 2 years ago. After about 12 months, the movement in the Y axis was unreliable, so I replaced the controller card, which fixed the problem.

Now, about another 12 months later, the Z axiz is unreliable. It will move, but then just make a buzzing sound and stop.

Are these machines inherently unreliable. I am only using it from time to time, so it is not overworked.

In general replacing the RAMBo once a year is definitely not something I would expect to see.There are a couple things I can think of that could be playing into your difficulty.
Do you ever use anything metal on your nozzle? If something metallic is touched to the nozzle it runs the risk of causing a static discharge that can damage the RAMBo (controller card) this could explain multiple failed boards.
It is also possible that this second problem is something else altogether. Could you post a video of the printer behavior when you try to send a Z-movement command? This maybe a matter of something like a stepper driver not getting enough cooling due to a dusty case fan or an out of level X-axis., both of those can also cause difficulty with the Z-axis. Seeing the printer behavior or getting some more information about the behavior during movement should help narrow down what is going on here.