Why not install a brand new flat vent Z-22? I did it to one of my SBBN007 and it is perfect. Looks fresh from the factory. I bought various Z-22 flat vent from Harry (Yobokies). He sells original ones for an unbeatable price.
I bought my 7549-7010 from an individual located in Hong Kong. This strap, "Seiko DAL1BP 22" was attached to it. It is a 22mm flat vent strap that is of firm quality rubber. I assume that like the 22mm Daloaz vent strap that came with the SBBN007 Tunas, this is the Daloaz strap that came with the 7549 Tunas. I have found very little results when researching the DAL1BP on the internet.