I don't know the cutoff dates, but it makes sense that the two and three connector types might have to be done differently.
I didn't hold the button down, just prevent it from rotating with the body. That keeps the wire from twisting.
The access hole is really small. maybe in 68-9 it was made bigger?
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I was able to take a peek at the connector with a mirror and small light through the access hole above.
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