3640 hours on my X1C that I got in early January
Yeah, I know, I have a problem ;-D
I printed mostly PLA and PETG, few kgs of CF filament (PAHT-CF is great), a tiny bit of GF filament, few kgs of ASA, some CPE, just a bit of TPU… I like to try different filaments and I like to put them to use, but I don’t print many engineering parts.
As far as service goes - I try to take good care of it. Regular removal of filament bits from the bottom, regular vacuuming of the bottom and any orifices where it might get lodged. I lube it at least once a month, but sometimes sooner (if I’m doing other maintenance), I usually clean my carbon rods at the same time.
As far as issues and work go:
I had some weird layer shifts, even with minor collisions, but I tightened the belts a little bit more and it got better and haven’t touched the belts since.
I just fixed a long-standing “issue” if you can even call it that, where I had a very slight play in the toolhead (it was there since the beginning and I assumed it was normal). All I needed to do was take the back cover of the toohead off and tighten top screws. The effect of that play was extremely minor, you could only tell when solid infill was going on where it would lay perfectly spaced parallel lines but if it were to jump somewhere and go back those lines would suddenly have an extremely small (but still noticeable) gap. We’re talking maybe 0.1mm, maybe even less. On fast movement, there was a bit of noise from it which is now gone (but I have several other noises I’m concerned about :)).
There’s been some slight squeal going on from the toolhead for the past month, maybe longer, which sounds a bit like an idler, but there’s no idler in there so I’m going to assume it’s some debris lodged in the bearing. I tried cleaning the rods and getting some IPA in the bearing but it didn’t help, so I just try not to worry much. Worst case - new carbon rods…
Carbon rods condition is adequate - you can see some marks on them, some are slight ridges, mostly in the center even though I try to spread my prints over various parts of the plate, and there are some scuff marks in places where I think I had some sort of collision in the past.
I have replaced the nozzle wiper once so far, and I haven’t touched the cutter, but I did maybe 10 multicolor prints and half of those was a simple color change at layer.
AMS was upgraded with a Hydra mod 14 days ago, I should have done it much sooner 
I sometimes got “failed to retract filament” error, part of it was me trying to “upgrade” with smaller diameter tubing (don’t do that, there’s no point in it with out printers), part of it was helped by the PTFE toolhead guide mod. I also have slightly damaged first stage feeders because I did lots of printing with fibre-filled filament (not carbon fiber, but colorFabb Vibers PLA which has elephant grass) - it just ate the plastic guide and dug a hole. Printing AMS guides and putting some PTFE tubing on it helped a lot, then when doing the Hydra mod I blew air through it and cleaned everything and so far so good, no errors.
I am on my third extruder - not because of the extruder, but because of the PTFE tube lock on the top losing the tiny metal guides. Waiting for Bambu to make it available as a spare part.
I am on my fourth or fifth nozzle, even a hardened one gets worn over time. For me, it’s not CF filament that kills it, it’s colorFabb Glowfill
print a spool and the end gets quite a bit flatter. I don’t think the hardened nozzle is hardened enough at all. None of the previous nozzles are unusable, they mostly print fine, but I just change it when I notice the end getting a bit too flat for my liking or weird issues with extrusion or the wiper not working as good as on a new nozzle.
I did bed tramming because I saw some rather large bed mesh movement, but I haven’t extracted the mesh from the printer I simply trammed it like described in the Wiki and then eyeball-tuned it according to what movement I saw on the camera and did bed leveling again. Now I get much less movement than before. But as stated above - I don’t print many engineering parts or even huge prints, so I can’t tell you how much of a banana bed I really have 
Some lurking issues
- That squealing sound coming from the toolhead, probably carbon rod guides - I’m not at all concerned about the cost, but I hate screws and I hate different length and size screws and this would be a huge job. Bambu, please make a hot-swap system or something on your next printer. That back panel could have some sort of quick release system, or at least captive screws or something… I don’t have a good workplace to disassemble the printer to bits

- Belts sometimes have strands detached in places. I snip them if I see them, I don’t think those belts are going to snap anytime soon or something like that, but I wonder why it’s even happening. Thinking about it, it’s probably the same strand as it shows up in the same place.
- Weird black debris accumulating on extruder gear… carbon rods? Belts? Not a lot, but it’s there after a while
- Weird black debris on the AMS buffer and generally on anything behind the printer - I’d bet it’s the belts getting worn out, but again I don’t think they’lll disintegrate anytime soon… or rather hope?
- Aux Fan is very noisy and was ever since I got the printer. Sometimes a tap or bump helps, I’m going to change it one day. I don’t think it’s the fan that is faulty but it looks like the glue pads on the back of it are detached (why didn’t you screw it all the way around on buffers, Bambu??)
- Chamber fan is insanely noisy, I turn it off whenever it turns on, haven’t looked into whether mine is excessively noisy or not compared to others
- Mainboard fan was noisy for the first month or two, a tap always solved it and now it’s not noisy anymore ¯_(ツ)_/¯
- Bed heater cable behind the third pillar looked like it was rubbing against the bed screw, so I put some PTFE tape around it. Support said it’s nothing to worry about and I think I concur. It seems to be static and not rubbing really, but to be honest I only just now realized I haven’t inspected it in quite a long while.
That’s really everything I can think of now.
TL;DR: I like my X1C very much, I haven’t had any major issues and whatever minor issues I had I was able to solve over time.