Bad first few layers on K2 Plus - problem only just started after long use of going well!

Hi all!

My K2 Plus seems to be having issues where the bottom 4mm or so of the print has weird marks on the outside of the print. See photo for reference. From what I can tell, it is something to do with the Z axis, but I don’t know how to adjust or fix the problem.

I’m printing with ABS, and have successfully printed heaps in the past, this problem is a new thing.

Any ideas?

Thanks,

Paul.