Some model builders use that model Paasche. I've only heard positive things said about that brush from its owners. Of course, there are naysayers who will say negatives about any single action brush. I used a single action Binks from 1970-2005, mostly with various lacquers. I was able to do good work over the years.
I would bet that Badger still has repair parts & gaskets that would get your black brush into good operating condition, if you wanted to. The gaskets on a brush that old are probably o-rings. They are on my old Binks.