Mamiya shutter

Hi everyone, i got a Mamiya 645 AFD with broken shutter (see image). I used this same camera until 5 or 6 years ago, and i remember this problem was frequent. Unfortunately, at that time i knew a german store with spare parts, now is closed and i really don't know how to fix it.
Can someone help me?
Do you know where i can find a new shutter, and what price do you think would be right for this replacement?
Thank you!