I’m usig the black velleman PLA also, no specific problems here.
the warping can also cause nozzle clogging. the part comes up near the edges and the extrusion is obstructed.
Try calibrating the nozzle to buildtak surface, or replace the buildtak surface if worn out.
Trying to print too fast (filament compresses and expands and then jams inside the isolator) or too slow(filament melts inside the isolator) can also jam the nozzle.
And you are right, nozzle clogging can occur gradually over time, periodical cleaning is necessary (~every 50hrs).