Like I mentioned before. I am not an expert. I only had mine for maybe 3 weeks. I bought it used as well. I went through it and tightened it all up. Blew some air through it to make sure its clean. I am quite sure there was a setting in the user panel (on the printer) to return to factory settings or it was "initial set up" ... take this with a grain of salt I am not at home ATM. Then it did some calibration, asked me to level the bed and it was done. PLA. Slowest I printed was 30 mm/s. That was a straight up tube with no support and only 0.4mm wall thickness. So I needed it to stick before falling over, and 90 was stringy. I think the recommended is between 30 - 90 mm/sTravel speed is also set at 150... but I turn that down to about 100 mm/s No need to make it work harder. Run that and see if there is any difference. Also make sure your table adjuster screws are not maxed out.