Weird Print Problem

So my Taz was running fine until I had to replace the head assembly. Got the new one with the ES stops printed on the front (ES856). Set the NEW ESSTEPS and stored, then did a 100mm calibration print. 100mm printed out as 100.5. Totally acceptable. I tried printing and this happened. With 3 top and bottom layers, the bottom is perfect but the top didn’t fill and I got these fish bone looking things on the side. Can anyone tell me what is wrong? Pulling my hair out trying to get it to print properly again. Forgot to mention: PETG Bed at 60, temp at 235. Extrusion multiplyer at 98%.

You are printing with a really really low infiltrate percentage for some reason, and the infill structure broke loose in a couple places, got stuck on the nozzle, relocated and stuck out of the walls. The top is failing because the there isn’t enough structure left to support the layer.

Set my infill to 50%. Still having the problem. Any other ideas? It looks like the filament is leaking out of the print head from piece to piece. There are 5 cubes on the bed like the 5 on a die. When it goes from piece to piece, even ith retraction, it seems to be leaking out of the print head. Then when it comes to the new piece, it sticks a little on the edge. Is my print head bad?

I had that EXACT problem just 3 days ago…

I opened a brand new roll of esun PETG, same as previous roll except for batch#. Suddenly had all those weird growths at the end of long travel moves, using the same gcode that printed perfectly minutes earlier (using the previous roll of PETG). I increased retraction amount and speed, but that didn’t help.

Exactly as you say, those “fishbone” artifacts were being caused by “oozing” during the long moves. I suspected moisture, even though I had just opened the reel which was vacuum-packed with desiccant. But after a manual extrude, I could see it continue to rapidly ooze and bubble out from the extruder.

I put the entire reel in a 150F oven for 6 hours. After cooling and retrying – it printed perfectly, without any of that oozing or artifacts.

So give that a try… 150F for 4-6 hours should dry out the entire spool. And of course, always store PETG in a sealed container with desiccant or the problem will return!

(Addendum… For the top layer: PETG tends to droop, so you either need denser infill, or more solid layers.)