extrusion problem, atomic method doesn't give solution

[Bigeye 1]

Hello,

I am experiencing extrusion problems. Very irregular prints with PLA. So I tried the Atomic method to clean the nozzle. But the filament comes out with a strange dent. Any idea what is wrong here?

Thanx in advance.

[Bigeye 1]

I tried the Atomic method another 4 times since I posted the last image of the filament after the procedure and it seemed to come out less messy all though not as perfect as I see on demonstration pictures. I tried to print a model (figurine) which went well for a while but halfway the problem reoccured. Thin, crusty layers and a lot of 'hair'. But some parts are printed well. I am using Simplify3D. Temp. 210º, Building plate without heating. I already cleaned the filament feeder. Should I replace the nozzle?