I have been printing PLA for years and am just starting to dabble with PETG. I had my bed heated to 75 deg C printing on Kapton with a brim, and the hot end was 230 deg C. (The printer still has the mk8 extruder hot end.) It worked! I printed a column with 10% fill and it came out very well. Print speed was around 35mm/s

Then I tried a calibration block and everything went downhill. The infill stopped printing cleanly and the top surfaces could not be constructed. I tried changing extrusion temperatures, different fills and nothing worked for me. Here is an image of the fill:

After seeing this I cut the first print (see first picture) in half to see what the fill looked like there and it had came out good. Not sure what caused the change, I know this material is more abrasive and has is hard on the ptfe and nozzle in this hot end and am curious if this is the only reason for the trouble I am having. Thoughts?