Knock box wiring testing help

[rhock99@epix.net (Ryan H)]

Any hints or procedures for testing the knock box wiring?
I've swapped two different (same PN) boxes and neither worked, and I still suspect a faulty knock system causing my car to have low power (no timing advance, won't rev past 4k, occasionally shuts off completely)
I have a brand new distributor/cap, could these be bad already? (The problem started a week or so after I replaced it, but I replaced many other things in that week, too).
Thanks.