I finally got around to testing them all. It turns out that of the 2 I already picked off the top of the stack, one works perfectly and the other works mostly but is slightly intermittent.
The remaining 8 are all either dead or not AY chips at all.
The remaining 8 are all either dead or not AY chips at all.
My testing was flawed, in fact all but one of the chips work. Pretty happy about that :)