I had a similar issue a while ago, but it seemed to have gone away, until last night.
(I rarely printed large things, most of the stuff fit easily in the center, this is one of the few occassions where I actually use most of the plate.)
The images below should explain the issue, but in a few words:
I've tried to print the Easter Eggs from Maker's Muse ( https://www.youtube.com/watch?v=Xy20tZjRBuQ ).
Somehow after a few layers, the X-position has shifted for about 1MM. (I think this ruined the print in the end, but that's not important right now).
When I move the carriage (with disabled steppers) from left to right I notice it gets progressively harder to do so.
I've repeatedly cleaned the rods from debris (I still have no idea where it comes from, though I know a few times it was from the filament which sometimes scrapes across the metal frame) and lubricated it using a silicone-based lubricant.
Any ideas what exactly might be happening, and/or how I can prevent/fix this?