Originally Posted by
he1957
The sound of that X axis manual move by itself is very loud and sounds like the bearings are shot. Take the plate off and try the individual trucks.
The other thing of note is the change in pitch of the motors across travel; this seems evident in both X and Y but what's interesting is the timing - it seems consistent in a distance/time relationship. A bit odd me thinks.
(The Z sounds a little tired too).
If everything checks out mechanically, then have a look at your power supplies. For the circle components, both motors are running, drawing more current. Sounds like a power supply problem. If you have an oscilliscope, see if there is ripple on the DC power lines (bad filter caps). Failing the 'scope, try a DVM on the power lines and see if there is a variation of more than a few millivolts between load and no load, between just X, Y and X and Y together.
I'm guessing there may also be a loss of power on one side of power delivery (A and B) but the machine is losing position.
Try single X and Y movements + and - and mesaure the distance (with a ruler), rinse, repeat - perhaps that may show if lost position(s) is/are random or consistent. If consistent, check settings as per previous post otherwise mechanical/electrical - perhaps both?
Belt adjustment is typicallly just a few elongated slots under the motor mount plate screws; there may not be much movement so if the belts have stretched, they may need replacing.
Just a few thoughts.