Mechanical question

[selbstdual]

Dear readers,

The attached assembly is given. Both barrels are fixed on a metal plate via rolling bearings. Distance center of barrel to plate is 5cm(1.97 inches). My aim is to always pull the big object(consisting of noble steel, 1mm) on both barrels via the other elements, two strong magnets so the barrels always are in contact with the big object. It seems that the Magnets must be on the line being formed by all points which distance from the point of contact of the form and each barrel equals.

How and where could I mount the magnets so this condition is met?

Regards

selbstdual

PS: On the last picture the magnets are not in the right position but I wasn't able to change their position. If there are problems in understanding, please tell.