I've posted here before and finally found the time to get back to figuring Nybble out. I managed to calibrate it, but now when I type "kbalance" in the serial monitor, instead of continuously switching between states, Nybble seems to move to an approximation of the "stand" position, and kind of stay that way, while the servos are still working. Nybble doesn't go into the "rest" position, unless I type "d".
A video would explain it better (sorry for the cars noise in the background, you should still be able to hear the servos rumbling).
The front left knee also seems to move a bit abnormally, but that is likely because I burnt its servo during incorrect calibration in the past and bought an almost identical substitute (it's still MG90D).
I don't know how normal this is or how to fix it. Please help.