Problem 1

So I installed a new earth connection and it was all great, until something weird happened. Up till midday, jogging the cnc went just fine, then after that for a couple of hours it worked like shit, meaning that the steppers were running in such a manner that the ballscrews was shaking, and even stalling a couple of times, all 3 of them on all 3 axis, and testing it in the evening again, it works fine again. I.ve reduced once again the driver setup to 800 steps, assuming that maybe the 1600 was the problem, but no. It does not matter.
It. been a bit stormy in the evenings, and sometimes the lights were flashing in the workshop, but not in relation with the performance of the machine. Strangely enough, it was working just fine when the light were flashing. (it may not be the correct word, but I mean, the lights were changing their intensity at short intervals of time), and around 1pm, when it was sunny and nice, the cnc was taking the piss.
This was yesterday. Today, I.ve tested again, and jogging it, it worked fine for a few minutes, and after that, the motors changed their noise and the shaking occured again. Like it shakes the ballscrews and so the whole gantry. Sometimes, pressing reset in mach 3 it makes the problem go away for a minute or so, and then it happens again. Then exiting mach 3 and coming back later, it seems ok again, for some time. The steppers sound fine and smooth, and just like that they change their noise and have a jerky movement. On and off, without any patern I can notice so far.

So at least we.ve excluded the ground problem. What else can cause this? Fluctuations in the electrical voltage? amperage to low set for drivers (4.9A Peak, 3.5A RMS set now, next setting is 5.7A peak, and on the steppers it says 5.6A, but the driver can go up to 7.8A peak, 5.6A rms)?

Problem 2

I wired up the vfd, I change Parameter 1 and 2 to value of ..2..(for communication port control), then wired the 4 control wires like posted before ..the gnd pin goes to ACM, the 0-10v to V1, 1st relay pin (5th in order) to DCM, and 2nd relay pin to FOR., and then in mach 3, in motor outputs, I enabled the spindle, step pin 1, dir pin 0, dir lowactive and step I tried in all ways, step port and dir port both to 1, then in output signals I enabled output 1, port 1, pin 17, active low not checked, then spindle setup, relay control with disable spindle relay not checked, motor control with ..use spindle motor output.. and ..pwm control.. both checked and pwm base freq to 100, then in spindle pulleys, nr1 max speed 24000.
And it does not work. It does nothing when i press spindle cw f5, although the relay clicks on, and the voltage at terminal 0-10v is 9.54v The vfd just shows 0000000 on the screen.
What have I done wrong?