XY repeatability problems

hello,
I'm using a mendel i2. things have been going well until this past weekend.
I did a pretty nice t-rex skull and then I started getting really bad prints.

It started with this:



which is weird because it cleaned itself up. I didn't do anything and it started working.

now everything looks like the bottom part of the print in the pic.

I've checked pulley set screws, belt tension, jerk is set to 20mm/sec.

I have tried adjusting flow rate. I'm at a loss for what to do next.

any advice is appreciated.

Check for anything that might be catching... a fan shroud or wire or something touching the bed or the X or Y axis mechanism?

Try a cube test print to see if you can isolate the problem to either the X or Y axis.

Check for play in the X and/or Y axes. Check the screws holding the printer together, motor attachment screws, etc... they loosen too.

If you're using auto-leveling, also check the Z axis.

well, I made sure everything was tight. it was.
I looked for anything catching or dragging. didn't find anything.

then in a hail Mary attempt, I greased the rails.

problem went away.

decent prints now.

thanks for the help.

well that was short lived!

printed 2 pieces and now it's back to the way it was.

I have noticed that my entire hot end moves. like, (when it's cold) I can wiggle the nozzle by 1 or 2 millimeters.

the connection between the heatsink and the wade's extruder is not tight.

is this normal? if not, any ideas on how to make this tighter?

thanks

Maybe place a shim or washer between the hotend and extruder.

It's definitely not normal. What hot end is it? E3D is always pretty tight, and if it's worn out it's easily and cheaply replaceable by buying a new heat break, heater block and or nozzle.
If your hotend contains PEEK, it may have run too hot and the nozzle may be loose. You'd need to replace the PEEK tube and put a fan on it, or to permanently fix the issue I'd get an all metal hot end.