This is really weird.
I'm using Pronterface and setting the extruder temperature for PLA at 200, then 220 and finally 250 degrees.
Pronterface tells me the extruder temperatures are rising to 200, 220 and 250 degrees.
Then I try to print and the PLA fails to melt.
The filament softens a little, balls up above the print bed and gets dragged around by the tip.