I make a lot of use of my TAZ 6 printer for a multitude of projects at my Makerspace, and at home.
( I use it at least as much, if not more than, James from X-Robots uses his… and that’s saying something )
After ~5000 hours of printing time, I was getting lots of wobble artifacts. I could gently twist, and even lift, the build plate. The corners would move almost 3 millimeters up, and 1-2 millimeters to the right and left.
After checking everything from Z-axis alignment, frame alignment and squaring, and belt tightness… it occurred to me to check the IGUS bushings. I never lubricate my axis, since IGUS bushings are self-lubricating and can actually be damaged by the application of oils or solvents. I did regularly wipe down the rods with a clean microfiber cloth, to keep them clean and free of dust and skin oils.
I was >shocked< to find out how much the IGUS bushings had worn down. The center channel was oval-ish, rather than round, on all four bushings. Compared to a new bushing, there was a 0.5-0.7 mm of wear along the vertical axis, and 0.2-0.4 mm of wear along the horizontal axis.
New bushings are available in the Lulzbot store for $14 : https://www.lulzbot.com/store/parts/10mm-high-precision-bushing-4pk
The IGUS bushings for the X axis also have worn, but not as badly. Again, they have worn much more in the vertical, than the horizontal ( 0.08-0.15 mm in the vertical, 0.02-0.07 in the horizontal ). I have not replaced them yet.
Put simply – after about 2000 hours, you should >definitely< replace your IGUS bushings along the Y axis to make sure you maintain the best possible quality prints. This is the trade-off between using linear bearings, and the IGUS plastic bushings. They wear down, even though they are self-lubricating. Even if you keep your steel rods very clean.
After replacing the bushings with new ones, and checking that the y-axis belt was correctly tensioned, the build plate was easy to maintain level AND my prints have the straight sidewalls and crisp details I expect from the TAZ 6.