Armature too tight - Bernina Activa 140

No one has documented that job. You may have to reach out to Shark or get a new motor. If you can remove the armature and commutator, you may be able to get the brushes in from the centre.

https://www.google.com/search?q=Shark+Euro+Pro+998A+replace+motor+brushes

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IF the presser foot lever is not working, the linkage may be broken and needs to be replaced. This is a common issue and will require a new lever or armature so you can operate the presser foot properly. Please have a trained technician do the repairs for you. There will be affordable parts necessary to fix the machine.
Cheers,
Embroidery Services
San Diego, CA

Turn off or unplug from incoming power. If possible use scotchbrite pad to clean armature. If it's a small armature, then an ink eraser will work well. Brush holding devices come in a multitude of different designs. Only replace one brush at a time. General Electric has several maintenance for customers websites explaiNing this.

Chances are there is thread stuck in the bobbin area

contact the one you bought the machine from & tell them how
tight the hand wheel is & see what they recommend

See solution I suggested 10 seconds ago. Hope it helps. Jimmy

There should be a small screw/thumbscrew on the armature where the needle attaches to the unit, screw it to the left, and pull the needle down to remove it.

It is quite common for some sparks to be seen in the armature but id it is excessive you may need to replace the carbon brushes if you can get them

motor inside the casing you have to remove the cover motor at the rear beside the handwheel of sewing machine loosen set screw or lift upside machine bed so you can see the motor and wiring circuit,if bottom cover is present loosen bolt remove cover you can check motor wiring using multitester setting to R10 set switch on and setting test probe red and black rod attaching the two terminal of male plug start pedal switch besure it was unplug on ac source if there resistance on the circuit and the motor.If negative result.Isolate checking the electrical circuit.check continuity of switch,if ok.check armature winding of the motor in two terminal of the motor, you have to pull out motor inside the casing first remove belt from the motor and handwheel.Loosen the 3 bolt from motor holder to the casing.In motor assymble unlock and pull out two carbon brush attaching tha armature brush replaced a new one pair of carbob brush and install back again.besure winding was not
burn out otherwise you to replaced the motor.

Self threading is perhaps not exactly correct, however there is a guide with an armature to release the guide to enable easy access........have a look in you manual

Also take a look at this image and move the lever to use it.....all will be easier to see with the needle plate off ....until you become familiar with the operation