My P2S has 1800 hours under its belt and now the front right Z-rod started to make a grinding noise. It’s now printing something that has a LOT of z-hopping and it makes the noise every time the build plate moves up and down. I can clearly locate the noise coming from the bottom of the z-rod.
I’ve done the regular maintenance periodically but never done anything to the bearings. Could this noise be a dead/dying bearing?
If so, what type of bearings are they and how much of a pain are they to replace?
Have you checked under the printer yet and taken a look at the z pulley and belt?
I haven’t. It’s printing ABS at the moment so I haven’t even opened the door.
I’ll have a looksie tomorrow. What is it I should be looking for?
Besides looking for any wear and tear, or misalignment, check for a possible loose Allan set screws on all the belt pulleys. I’m assuming they have set screws.
Aside from a crunchy bearing, that would be where I would be looking.
The standard Bambu maintenance includes cleaning and lubricating the linear guides, which lubricates the linear bearings. Exceptionally unlikely the roller bearings would have an issue.
Without hearing the noise it’s impossible to tell you what it is, but z-hopping is such a small distance a bad bearing probably won’t make a noticeable noise.
I’d stop the print and get to the bottom of it, or at minimum post a video of the sound so we can try to advise you better.
I finished the print, cleaned the z-rods and put some fresh lube on them. Also dropped a little oil on the bearings. Ran the build plate up and down five times and didn’t hear a sound. I’ll recalibrate the printer just in case and print something tomorrow.
I hope the sound went away. If not, I’ll check the belt and the pulleys.
I did try to post a video in the original post but the forum wouldn’t let me. Said something about the file type being wrong. 
Try uploading the video to google drive and sharing the link