If you already have the bellows, you can ask Richard Ritter to replace them. I did it last year with a Wista 4x5 woodman, and I can recommend based on the quality of work, turnaround time, and reasonable cost.
I too had Richard Ritter replace my Wista DXIII 4x5 bellows about a year ago. He supplied the bellows and it along with his craftsmanship the replacement was better than the original.