I have examined the parts list of your furler on "Spare Parts List Furlex 200 S & 300 S - Seldén" site and think that the problem could be two things: 1-One or many seat(s) for the ball bearings is(are) broken, or: 2-The forestay has broken strands inside the extrusions which stops the swivel from turning at regular angle in both directions. The second option is probably most probable.
Unfortunetely, you will have to dismantle the whole unit to examine, but the good news is that you may have saved your mast from dismantling because if strands are broken,your forestay could have failed under heavy winds.
To remove the whole unit without taking down the mast, you have to tie the jib halyard tight to the front deck or balcony and then remove the entire unit. Remember: Have the mast secured good to the front before taking off the forestay with the furler, and put two halyards if you can to be double secure!
I have seen the top swivel seized and the furler would move at the bottom as the extrusion would twist. If no movement at the spool the problem must be in the lower bearings.
Still check the forestay while doing the work.