Like Fazerider said, if You did not remove the part in the middle - garage must have lost the ball. I had same problem after fitting new plates and EBC springs. Could not figure it out for ages. In the end went back to old springs (actually to 6 long ones off Thundercat - they are identical - loong story ... and it worked. It seems to me that heavy duty EBC springs are too stiff.

Thanks for feedback guys.
@fazersharp  I wanted to try with polished swingarm first, black (or red)  were options for the future but since I crashed it recently and won't be riding for a year+ due to injuries I'm considering RSV Mille front and rear. Tail piece was made by a friend ( 3 afternoons + bit of modelling clay, plaster and glass fibre:).