Under extrusion and mixing after filament change on m201

[certeza]

I am using the m201 printer.
I replaced the PLA filament on the left extruder.
After the change there is a serious under extrusion problem. All surfaces are open.
Furthermore the printer mixes the 2 filaments in the first 2 or 3 layers.
But settings are for first filament 100% and second filament 0%.

I didn't have these problems before I changed the filament.
And I didn't change the settings.

What could be the cause?

I use the old firmware because I am waiting for issues in the new firmware to be fixed.

[Mark]

I think this is the filament left inside the hotend that caused the first 2-3 layers mixed. Maybe you need to clean the hotend totally.

[certeza]

You are probably right.

Is there an instruction manual available how to do this for a 2-in-1-out hot end?
I am afraid that I will damage the hot end.
This is still a bit new for me.

[Mark]

unplug the PTFE tube and heat it up to about 200 degrees and unscrew the two setscrews on the side of the heater block to clean it. And make sure the PTFE tube is inserted to the bottom of the hotend when you finished the work, or it might clogged.

[Malaka]

I've had plenty of clogging issues with my M201, I recommend disassembling the whole entire hot end assembly and using the small rod given, I would spin it while inserting into all holes of hotend and collecting melted plastic. If you unscrew the two tubes which go into the heat sink, notice it might have a small thin hole around the inner diameter, it might be white in color. This is the cooled/burnt filament which doesn't really move and cause your filament to push through rough. If you melt this, it becomes black gunk, You have to clean this out and insert the filament tubes nice and snug, as deep as you can or else it will clog up again when the filament cools. Be careful with the hotend and try using something soft to clamp it, I've scratched mine up holding it with tools as I work/unscrew things on it. Also try removing the nozzle and using the same thin rod tool to dig in and try removing the plastic. You will need to bring the Z axis all the way up and move the bed all the way back to access the nozzle hole with the rod. Keep in mind, none of the pieces will unscrew off the hot end if you don't heat it to at least 190-210 Celsius.

Note, the issue with going with the whole 94% 6% or even 100% 0% will cause clogging issues. What happens is the filament will travel back up the second extruder tube, cool and cause a blockage which requires disassemble to unclog. I've noticed best setting will be 85% max for one extruder or else you might risk clogging the second one. The purpose of the M201 is for mixing, so forcing 100% can be detrimental for the other extruder, usually you might notice clicking of the second extruder cause its struggling on a clog.

[certeza]

Thank you, this is all very helpful!
I recognize all the symptoms you mention.

One thing is, I tried to unscrew the nozzle but I noticed I was damaging the hexagon sides.
It is screwed on very tightly!

Would it be better to first heat up the hot end and then try to unscrew the nozzle?