Model Extruder Clicking

So I’ve been using the inventure about 3 years now. Since 500h I always printed the same gcode, same material (Petg) out of dry boxes, everything went fine. Except for the first hotend leaking above the heatblock.
I am now on my second Hotend Module. 60h of printing went fine.

But now the extruder started clicking and underextrusion occures whenever it reaches higher printing speeds. Mainly inner walls and infill.
So I disassembled the hotend and have done the maintenance, like i did when changing the hotend module. All filament paths are free and smooth.

-Extruder gear shows no wear, when I checked it against a flat metal ruler. I already ordered a spare gear just to be sure, but that didn’t fit onto the shaft… hope the sales team sorts this out.
-Changed the nozzle too, which didn’t solve the problem.
-Fan check is good, the fan on the stepper drivers at the bottom runs also strong
-Filament feeding tube is smooth

Could this be an electronical issue?