My nozzle wiper regularly clogs. Is there any solution?
Mine doesn’t get that bad, but I do see where 2 or 3 get stuck together. Seems like purging amount is very inconsistent and it tends to leave a long strings sometimes, maybe there is a need to tune the filaments better.
Firstly make sure the wiper spring is not bent- if it is bend it back or replace it. secondly coat the Shute with graphite powder. -works perfectly 
You mean this with spring?
I somehow have the feeling that the lever at the back is not pressed properly by the print head
Yes, that’s the part, however I didn’t need it , I just bent it back up with a small screwdriver & it has been working fine, I just get the odd extruder clog 
. The graphite powder will solve the extruded filament sticking to the waste chute.