I would not recommend the vice technique on a knive that has one-piece solid handles. The potential to fatally crack the handle is just to great. However, you said this is an older knife. Many older knives have handles made from sheet metal bent into a U shape and then some other material secured to the sides to give width, a grip surface, and, of course, for decoration. In this case, the vice technique, carefully applied may work.
Otherwise, if your knife is a Benchmade, return it to the factory as they do have a life-time warranty. My guess is that they'll replace the latch.
If it's not a BM, then you can look around for a custom maker who can replace the latch for you.
As for learning new techniques, there are several books and videos, but if you've been flippin' butterflies long enough to wear out the latch on two knives, I'll be those will have little to teach you.
I find tricks two ways. First, I often put on music and try to keep the knife going to the beat at all costs (fingers, that sort of cost) and with minimal repetition. In trying to keep the knife going, I sometimes find some new thing I'd never done before. Isolate it and work it.
For example, Jeff Imada's books and videos will show you several manipulations that begin in "forward" grip (blade pointing away from you), and end up in "reverse" grip (blade pointing toward you). But, he shows no manipulations that being in reverse and end up in forward. Those are, apparently, left to the reader as an exercise. This creates terrible problems in if you want to manipulate the knife continuously for several minutes. I had to develope those techniques myself.
My second technique is simply to think about how I want the knife to look when it's moving. Then, I work at finding a way to achive that.
If you get really bored, try working on on toss-and-catch tricks.
Chuck