Oh what about that bearing? Maybe the bearing is going out?

Actually, when you put it that way - I can totally see your point I have 3 large footprint printers but x and y are really what used most, for big z index prints I have a print mill

Are the teeth worn down? Maybe it’s time to replace the gears. (Throwing stuff at the wall here) other than that it sounds like maybe there is a piece of filament stuck somewhere rubbing against the gear?

800x800x 200??? That’s the weirdest damn dimensions

~~ haven’t seen anyone mention this somehow, but this is most likely caused by a draft hitting that part of the print and causing it to cool at a different speed than the rest. Easy test, get a big cardboard box and put it over the printer and redo the print. You might need to invest in a cheap printer enclosure ~~

Edit: never mind I totally missed the part where you mentioned you had a heat enclosure