Regarding damage to N connectors:
It's not known very well that there are two different sizes of N and BNC connectors to be used with 50 Ohm or 75 Ohm cables. The center pin of the 75 Ohm connectors is larger than for the 50 Ohm connectors. Mating a 75 Ohm connector to a 50 Ohm Female N will result in damage to the Female. This is more common with BNC connectors.
Also, a poorly made N cable connector can have the center pin protruding too far. This can also damage the N Female. In my tool box, I have a guage to measure the center pin depth of N male connectors. This failure is not so common today with crimped connectors, but it's worth checking older cables for fit.
-ken-
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Ken