Update: Each time I had a key that bounced, I pulled the key cap off and sprayed a very small amount of DeOxit D5 on the contacts. After actuating it about 20 times, no more trouble :)
The other issue turned out to be self-inflicted! As I mentioned, the keyboard has (at most) 2-key rollover and I type fast. When hooked up to simulated TSS/8 at 110 baud for the TTY experience, it was easy for me to overrun and cause a misfire. A real 33 ASR (I have two) won't let the typist go too fast because the next key is physically blocked. At 1200 baud I can type normally, although I still have to pay attention to fully depress and release each key.
