I don’t think that will fix it - here is a slice in Simplify3D and it shows the problem I was describing (but really bad) see there the line come off the phone case vertically - that is a HUGE z shift - so it gets to that point, then lifts off the phone, then comes back down and carrys on but you get a large strig of plastic.
If you are happy editing gcode (a good time to start then slice the case - save to gcode and open the code in notepad and you will suddenly see a Z that is way out at about line 151563
Edit the z so that there is no change and save the gcode back as gcode and you are good to go
If you are doing it on a UM1 then I can do that for you here and email it.
OR - you can download meshmixer free and ‘heal’ the wound.
OR go back to joris and ask him to have a look.
I don’t think slower will fix it - if you want to test t then just start from just below that point (tell your UM to push it into the print bed)
I have printed a couple of cases already but not the day 4 one! I will let you know when I do.
I looked at it though and I must agree with all other opinions on this talk: temperature and/or speed.
Maybe your fan is not on or directed properly? (but then you would have more problems ! )
Attached an insight look because there are multiple problems with this case and I would like very much for you to go to Joris and ask him to fix this because it is not doing anybody any good!