@phaedrux, @williamwestonn My first reaction to seeing the example photos was that it was a mechanical problem. However, since only the electronics were replaced It seems unlikely that a new mechanical problem was accidentally introduced. So the problem must be with the current settings. Running bed auto-tune and implementing PID is easy, and I offered this as a suggestion because it was something that I would try if this was happening to me. It is a more precise way to control temperature so I still recommend it.
I have Delta that is using microstepping interpolation, and also have an Ormerod 2 cartesian that has microstepping interpolation turned OFF. Here is a thread about why this is recommended:
https://forum.duet3d.com/topic/79/microstep-interpolation/11