I used 0.16 layer height, I think 0.3 is much too wide for the UM2, would give really rough prints.
Ht 0.16mm, base and walls 0.8mm, fill 20%. Black PLA on standard settings, 210C and 60C bed.
One of the scissor arms had some fusion points, hence the gentle prising apart. Work the screw a bit, find which bit is sticking and try to crack the fused bits with a tiny screwdriver. The screw thread was perfect, as were all the pivot joints. I see to remember it was the left hand side, ( looking from the screw head ) that was stuck. If you gently pull the jack apart by its top and bottom you will see which part is sticking.