I’ve had the Ender 3 for 2 years and had problems with bed sticking and poor prints until I found if I changed the extruder feed to 150%
I checked the feed rate and and was the default of 96 steps/mm
I ran the test extruding 100mm and it only extruded 40 mm
I had to set the steps/mm to 240 to get it to extrude 100 mm
Now prints are much better looking like moulded plastic parts
There is no slipping of the drive and it extrudes the same in both directions
Is it possible that the stepper has been changed to a micro stepper
Not sure, but I do wonder if the PTFE tube inside the hotend has shrunk in diameter like mine has done in the past. In particular, if you haven’t changed the tube in 2 years and/or you’ve found you’ve had to increase the flow rate more & more over time, I would be checking the tubing: [U]Live & Learn.... I Guess (Again) - MakeWithTech Community Forum.
That’s good detective work. Glad to see it’s resolved. On to printing… 