Thanks to all of you guys. Problem solved, with screw extractor.
Process: increased contact surface to screw extractor by pre-drilling with 2.6mm driller. Used M4 screw extractor. Warmed up the motor with heatgun until "hand warm”, and appied a bit of bicycle chain grease from the backside to the thread. stabilized motor with clamp and applied good amount of vertical pressure on screw extractor while turning.
Learning: the motor is attached to the outer planetary gearing host (this plastic part : JXHSV06-08003-d Gear Seat_3”) with two screws from the gear side. the holes in the the motor, where the cross headed screws are located, have a threading at the end inside the motor. so partley the screws are only of cosmetic nature. (forgot to check if it is true for all four of them)
2nd learning: dissambly of the extruder is easy
following up question: wanted to replace the fan for the noozle cooling with the “nautilus” setup hosting a 5010 fan. but I have the impression that the air output is far higher than the tip of the nozzle. Should it be like this? Thought the fan should speed up the cooling time of the applied filament, not cool the nozzle? Edit: already solved. Guess I used SV06 version not SV06+ version. There is a remix in the net, for a taller version.