I tried printing this using the same gcode that I had successfully printed this with only difference being the filament color oof the same brand. I have printed several of these using different filaments and the only other time I had the issue was when I tried to scale it. From all indications the layer shift was caused at the head which has the least contact point of any of the other parts except maybe the tail. It was sliced in Prusa Slicer which I what I mainly use. When looking through the preview layer by layer I see no issues.
The problem is probably the temperature or the filament itself. As you said you only changed the filament.
It could be some diameter that caused a clog. The extruder is pushing and at some point the filament gets free, releases the build up pressure and purges a blob. On the next layer the tool head is hitting the blob and skipping steps.
Same can happen if the filament you used has a different temperature range. Especially when on the lower end of that range you may enter the less fluid section. Again the filament gets stuck a little, gets free, releases the pressure and a blob escapes, which the printer hits on the next layer.
A third reason could be also temperature related. The filament is hot, but the viscosity is not as good as with other filament. Yes, this is the last argument, but it could be that your printer is out of his specs and not the filament. The printer is just not able to push the filament fast enough, even so it should be able. In this case you need a little more power to the extruder motor, because it is setup to weak. So setting the temperature a little up is probably the easiest solution, even so you should fix the real issue.
One could say the same about the x/y motors as skipping happens as they fail to keep position, which is the reason of having not enough power or skipping belts. While checking the belts is a good idea anyway, your printer works fine when not hitting anything, so x/y motor power should be fine. We should fix the reason which caused the bump in the first place and not overcome the bump with more power.
It does not take much of a blob to cause a layer shift, but it happens more on modern printers as with old ones. On modern printers “we” use blocks instead of springs under the bed (or even fixed beds) and there is no way the tool head can flex away, as we at least upgraded them to reduce flex. I see that often on the first layer of my Anet ABS printer, when the ABS glue is uneven and the tool is bending and plopping over bumps, while the bed is pushed down. With modern printers this would probably cause a layer shift every time.
Finally got around to trying the Red Eye Crock again, I cleaned the bed with soap and water. Tried printing and the head came loose no other layer shifts. I then put glue stick on the bed and upped the bed temp to 65c, success!!
Must be something to do with the color, the 1st one I printed was with he same brand filament Coex Bone Brown, the problem child was Coex Blood Red both PLA. Had also previously printed it with Plolymaker Pink and Hatchbox Yellow. Of course using different filament profiles for temp control. The slicing setting were the same for all of them.
