XYZ Calibration Failed  

XYZ Calibration Failed

Hi! 

Lately there's been some weirdness with my MK3 and today it stopped working completely. Timeline:

1. For a few weeks, when I enter a specific folder on the SD card, the printer head starts slowly sliding right with a weird noise. It does this for a few centimetres and then stops. It hasn't caused any issues. 
2. Today, while printing a file out of that specific folder (out of which I have printed many files before without issue) I had a crash and aborted. It happens every now and then (every couple of weeks at constant, almost round-the-clock use) so I didn't think too much of it at first.
3. I tried again, but now when it went to home before the print, it thought home was a bit to the right of the middle of the bed (where it went after the crash before). 
4. I rebooted and told it to auto home. It went to the same spot.
5. I updated firmware, which was apparently the 3.8.0
6. I tried to auto home again, but it went to the same spot.
7. I shut it off and manually moved the head to the far left, booted up and told it to home. Now it worked.
8. I told it to print that same file again. It finished a small portion of the first layer (about 5s in) and then said crash detected, went to that spot over to the right and resumed printing. I aborted the print.
9. I tried to home, and now it went to that spot over a bit to the right of the middle of the bed again. 
10. I did a full reset and used the Wizard. During the XYZ calibration (where the head flies in little circles while you hold a paper underneath) it did not catch the paper while doing circles, but did catch the paper while slowly going back and forth sideways. On each of the four points. I thought it weird but let it continue, since there was no catastrophic failure. I checked that there was indeed no filament sticking out from the nozzle. 
11. I tried printing again, same error: printed for a few seconds, crash detected, resumed on the side, i cancelled it, auto home was in the wrong spot through reboots until I manually push it all the way to the left. 
12. I noticed that the auto homes that went to the wrong spot also pressed down hard on the spring steel sheet, leaving dents in it. I tested the Pinda probe with a piece of metal and the light reacted, so that one seems fine.
13. I cleaned the X-axis rods and put some new PTFE spray on it and moved the print head back and forth a bit, because I know the X-axis has been making a lot more sound than the Y-axis for some time and I could tell it was a bit dry. Maybe even a ball in the bearing was stuck? When doing this I noticed a scratch running along the upper X rod, so clearly a ball is stuck. 
14. I tried to do a full calibration Wizard again. I noticed that when it homed at the start, the Pinda probe was not above the little circle on the bed. I don't know if it's supposed to be? The probe was about 1.5cm away in both X and Y direction, towards me and towards my right. This time during the Wizard, the paper did not catch in the first two corners, but after finishing the second corner it said "XYZ calibration failed. Bed calibration point was not found." 
15. At this point I and my 3D printing senior on the phone gave up and came to you lovely folks. 

I have a normal MK3, (not the 3S) and it is about a year old. I have used it around 16-24 hours a day for maybe 85% of the time I've owned it (all the time except on vacations) and this is the first issue I've had with it. It's the build-it-yourself-kit and given that it has printed 15-20kg for me already, I think it was assembled correctly. 
Any ideas?