Rock-Ola mechanism magazine "shuttle" clogging

Hi, I have a problem with my seventeens R-O 451 "shuttle" not following the A/B groove. It stays on the "b" side and randomly blocks everything and stops the rotation. Then the magazine motor won't turn. An till I disengage the motor and manually turn the magazine i bit backwards it releases but won't change the groove.
Is there any other possibilities than a clogged "changeWay", can the cast suffer damages?
Where can I found one in good condition?
Thank's for Your response

matti55
finland