Have a problem with smart extruder (type 12.2.1) on his printer. Model of printer is MB 5th Generation 3D printer, and the printer is new.
When he like attaching an extruder, the printer make an error about extruder attachment.
Only when put a plastic tail around an extruder, printer recognized it.
I tried with different type of extruder, but the problem is the same.
I check connector pins, but they are OK
Firmware is up to date.
* The air plenum on bottom of extruder is missing (see attachment). Is this a possible reason about the problem?