You defenitely have a mechanical issue. In the first picture it has been since 1912 that we had 47 states. The other two pictures your problem is getting worse. Like Will said check your pulley set screws that at least one of them is over a flat spot. Some people replace those set screws with 10MM long cap screws. It is easier to tighten them and not strip them with the tiny allen wrench used for the stock ones.
Roll your gantry with the power off front to back and side to side to the limits. Do not move too fast or you will get Electromotive Force that sounds like a belt slipping. If you laptop or computer is hooked up to the powered off machine you may hear the windows sound for a device connecting and then unconnecting.
Pull on your gantry ends up and down and side to side and the Z carriage the same way if it is a Belt Z, the HDZ and Z-Plus do not have v-wheels but the X axis does… If you have loose or damaged v-wheels you will need to adjust them and/or replace them. I have attached a draft copy of a procedure to test for homing issues. The back of the doc is a procedure for adjusting your v-wheels. The v-wheel adjustment starts on page 8.
homing_problems.pdf (1.2 MB)