Steps /mm shifted

I upgraded my X-Carve 1000mm machine with the Ultimate Upgrade from cnc4newbies. I had my machine calibrated with the $ settings for as follows.
$102= 49.06

Everything was working correctly. I could cut a 2 inch square that was 2 inches X and Y.
I was using G-Code to move the spindle to the back of the machine with this code: G90 G21 G0 X450 Y800.
It should have moved the spindle to the middle of the X and the back of the machine. What it did was move X all the way to the max X and Y to the correct point. When it went to the max X it jammed and made a grinding noise.
So I Homed the spindle and tried to carve a 2 inch square. The cave was 4.5 inches X by 2 inches Y.

I changed $100=64.9 and it carves a 2 inch by 2inch square.

This does not seem like a good thing. I am wondering if the X stepper motor was damaged when it jammed the x limit.
Any ideas or should I buy another stepper motor and see what happens.

If the ultimate upgrade includes threaded lead screws over the timing belts, you’ll no doubt have to do the math to adjust your 100, 101 and 102 accordingly from what they were. You didn’t say if you did that or are just trying numbers.

Just as an example

A stalled stepper (making grinding noise) is not harmful and pose no threat.

Whenever a change is done, that change the amount of travel per stepper motor rotation a recalibration of GRBL step/mm parameter need to be done.

Math is current GRBL value divided with actual travel multiplied with intended travel
OldValue / ActualTravel * CommandedTravel

Found the problem. When I was turning off the auto torque reduction in the x-controller, I inadvertently changed the X micro step value from 1/8 to 1/4. I have corrected the value and now the settings are correct for the 100 value.
Thanks for the insights

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