Accelerometer fails on X Axis  

Accelerometer fails on X Axis

Greetings everyone,

I have a MK3.5S (with MMU3) and a CORE one. Wanted to calibrate IS this weekend but I am running into an issue specifically with the MK3.5S. On the CORE One, calibrations runs through flawlessly. But on the MK3.5S the calibration completes and then tells me that the frequency of the X-Axis is too low and that I should tighten the belts. But, according to the Prusa Belt Tuner, the X-Axis is calibrated "Just right" (100Hz), even after tightening the belt to 120Hz+, I still get the Error that the frequency is too low.

Then I thought maybe its the MMU3 sitting on top of the frame, so I held it in the air the entire calibration, to no avail. I am currently at my wits end. Yes, there are some modifcations to the extruder, mainly the Visiflow fan duct, the Revo Hotend and of course the MMU3 tower, but I know I was able to calibrate IS once, a few weeks ago. Since then nothing hardware wise has changed.

I am using this mount for the accelerometer: https://www.printables.com/model/1113301-prusa-accelerometer-alternative-mount-for-mk35s

According to the comments at least one person reported no issues regarding the orientation. But just to be sure I taped the accelerometer in the "correct" orientation, but also here, X-Axis frequency too low, please tighten belt. Funny enough the Y-Axis value was the same as with the printed mount, so it was actually taped well enough to be able to give out correct values.

Anyone who might have an idea what's going on here?

Best regards.