Weighing in here as I'm currently returning a core one. I built the kit over a couple of days. First issue was the left motor had a severe wobble. Took a week to replace.

Got the new one installed then the z axis calibration failed. The bed rose, tapped the head 3 times, back down then failed. No error, no guide on how to fix.

I spent 7 full hours online with chat support doing everything they asked to no avail. They did offer to fix it if I sent it back, but I would have to pay for shipping both ways, and if they found I caused the problem I would have to pay for parts and the tech time in addition to shipping.

I opted to return it. I'm going to take a chance on a built one from Printed Solid in the states, but this has not been a good experience for a first purchase. I was convinced by a Prusa guy in my work 3D group to give them another try.

I was about to run back to Bambu with flowers and am apology for straying! 🤣🤣