My CR-10 prints are coming out very rough only 2/3 of the way through

I'm using esun Petg on a CR-10 and yesterday I printed a 15 hour long job for a small flower pot but strangely it appears as if the first 1/3 printed ok, then the 2/3 printed super rough and the last 1/3 printed ok again. :confused: See attached pic.

My settings in Cura are the default for this printer and for the petg I have it set at 240 nozzle, 85 printbed, layer height 0.2, speed is at 40, retraction distance 5 and retraction speed at 40.

I'm fairly new to 3d printing and I've been using these same settings for a few weeks with no problems but this is a new problem with all my prints lately. Any suggestions will be greatly appreciated :cool:, thanks!
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