Im in same boat as you all, printer is 4 days old and today VFA on x-axis was very apparent on a black PETG print I did.
All using the Standard Bambu profile.
Hold that up to your belt and see if the artifacts are in line with the cogs on the belt.
Will check tonight when home from work, but I think I already know the answer 
There are 5mm dowel pins with thread down the center to allow them to be pulled out instead of pressed through, might be a good replacement for the stock ones for easier future removal once they have been taken out. I believe the original should also be able to get drilled and tapped to be pulled out the top, doing it at low speed in a proper drill press would be advisable.
Iām not sure about how much torque the current pin/seat can take before it would start spinning, so if youāre going to try this, probably go with M2 or M2.5 tap size. OD 5mm M3 304 Stainless Steel Female Thread Cylindrical Pin Locating Dowel Pins | eBay
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So yep, they line up perfectly with the belt 
Contacted support today and the only thing they advised so far was to clean the rods (on a 4 day old printer). I did and even slowed down outer walls, but still same pattern. Also itās both on Y and X, not only X as I thought initially, because it was less pronounced on the previous model due to it being round.
Well, I can guarantee you that the OEM pins, if they are not threaded already will spin in the housing before you get them drilled let alone tapped, so it will have to be done after the fact which will be moot.
Now we need to find someone willing to void the warranty and replace that smooth idler with a cogged idler and see if that solves the issue.
Too early in the season for me - no disposable income.
If the P1Ps are doing it as well, that would be a cheaper pinch to void a $700 printer rather than a $1200.
Who ever does it needs to document, pictures and before and after prints for proof to submit to BL and maybe we can get this issue resolved for everyone and keep the warranty even if all BL does is provide the part and instructions to everyone. I doubt that they are going to say āWell ā ā ā ā , send them back and we will fix itā. That is cost prohibitive and I rather like the current price point for these printers.
The only time this is showing up is on large smooth surface prints and the majority of us are not. Mine is starting to be hit and miss, at least the last batch I printed was in white and I donāt recall any banding on them.
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Sticks, what do you classify as large smooth surfaces? Mine shows on small 20x20x20 cubes and 50x50 x10 blocks neither of which I would call large smooth surfaces!!! Cheers
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Rovster, where is this VFR test that you mention ?? thanks
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Bambu Studio Softfever > Calibration > VFA
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where do I find it? is it inside the program or somewhere else??
thanks
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Disregard the last, I have found it, thanks 
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Iām researching smooth belts
Seems easier to swap the drive motor pulleys
I will likely give it a go when Iāve got time, worst case scenario for that not working is putting the factory pulleys on the drive motors with the regular belts 
Polyurethane Round Belt, Smooth Surface High-Performance PU Transmission Belt Urethane Round Belt for Drive Transmission Orange(6mm*10m) https://a.co/d/02I7oaW
What kind of tension will you need to apply to the drive pulleys with a smooth belt system?
Iām not sure just yet as thatās still to be tested when the belts arrive
But my starting tension will be just what the tensioners allow which I think will be enough
Currently Iām trying to figure out a solution for the stepper motor drive gears as they will need to be smooth so the belts donāt get chewed up
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I too have the same ringing/VFA issue. The printer was working fine for about a month, (50ish hours prints time) and then all of a sudden similar to the above issue, I know Bambu is going to say clean this and that, I posted in the FB group and done all this morning that they advised apart from change the extruder. No joy 
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Happy to see than other people are sad about this issues. On Facebook, nobody speak about thatā¦
I follow a topic on discord about that too, some people think it come from the extruder.
I hope we can find a solutionā¦ Love this printer, but this issue is a very big problemā¦
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any news?
I would like to swap the pulleys
Or have anyone skills with 3D Drawing and can make new X Y Carrier?
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What changed after 50 hours, did you start using different filament? I noticed Generic PLA has a much lower flowrate. I thought my printer had gotten worse and started to show these lines as well. At least on my printer it was cause I had run out of BambuLab filament and started printing using some other filaments and changed to the Generic PLA profile. When I set the flow rate to the same as BambuLab PLA (21mm^3) the lines disappeared. So in other words the problem always existed on my printer, just didnāt show up with BambuLab PLA.
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Hi, Bambu Lab replaced my printer. I got new version, with 90 degree hub connector, new toolhead (new board and extruder sock) and belts (now there are inscriptions on them).
The first print was checking for the VFA.
It little bit better, but VFA is still here.
After you change the pulleys, pls, share the result. If it will help - I will change it too.
Was digging through my old archives and found a little video back from the times when I was building a HyperCube. And find it rather related to the VFAs we see on BL printers
Just to put those who unaware into perspective- HyperCuber was and old printer design that is somewhat similar to present BL printers. It had one place where the toothed side of the belt was running over a smooth pulley. Heck, it even had carbon rods on X gantry
So, the point of interest starts at 00:17. Just watch the dial indicator needle closely:
- Fine and fast jerking is caused by the teeth riding on the smooth pulley. IHMO, the same thing is happening on BL printers, causing VFA
- A bit higher amplitude at a lower speed - that is induced by the eccentricity on one or several pulleys
- Huge leap when the direction changes from X+ to X- (and vice versa) - that is a little slop in Y bearings allowing the X gantry to skew
Note that the indicator is set to pick up its readings from X rod. So its the whole X gantry moving back and forth in response to change of the belt tension
Now, generally, this video shows how sensitive CoreXY machines are to proper and constant belt tension. Even small alterations caused by a belt tooth getting on or off the smooth pulley can throw it off.
PS: posting this here as a potential aid in visualising why proper pulleys matter.
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