What would cause theses non horizontal wavy lines?

[thingamajig]

I have a X1C and I have been getting wavy lines that are not horizontal on these vertical walls. This part has printed fine for months until last week.

I have tried 3 different brands of filament so I have ruled out a filament issue.

I have replaced the extruder and hotend with brand new ones so I have ruled out the extruder, nozzle, hotend, and thermistor.

I have loaded the filament from the external spool so I have ruled out the filament hub and the entire AMS.

I have not changed software, firmware, or the model so it’s not a software issue.

I am out of ideas. Please help!

[3DPotter]

Did you end up figuring this issue out? I’m having the same issue but only on one of my three X1Cs, so I’m sure it’s not GCode or firmware related. It’s not too bad on flat surfaces but its horrendous on cylindrical surfaces.

[thingamajig]

Yes, I found the cause of the issue. At the top of my front right lead screw, there’s a small silicone sock that helps keep the lead screw centered in its housing. That sock had popped off. Once I reinserted the silicone sock and made sure everything was seated properly, the problem went away.