Ok i have been trying to print a the Bottom of the power supply so i can add a on/off switch to my Prusa Knock off. I have noticed a really odd thing. I'm doing a 500 layers, the first 150 layers are perfect, then 150 layers are brittle, much like its under extruding, pourus, then the top 150 layers are fine.. Basically the middle of the print is bad. If it was good and then got bad and stayed bad it would make some sense, but its great, crap then great again. I have printed this box 4 times and its the same every time. its like the printer can print perfect up to about 10CM, then from 10CM to 30CM its crap, then 30CM + is ok again. I have switched filament, 3 different ones used with same results so it seem its the machine. It got all the marking of poor extrusion, but why would it be ok, bad then ok again in same print? MY spool is free, no binding that i see. I am having fun, but 6 hours a print and all failing is starting to get to me I have change layer height, even went up 10% on flow, still same in middle of print. I know this is a hard one I see very little like this when i search.