I've noticed some stamped chain link sterling jewelry having a weak magnetism when held to a strong magnet (not the average fridge magnet but stronger) does get attracted — why is this? is the the tiny amount of non-silver metals in sterling doing this? is the .075 nickel or iron?

Answer:
Nickel is magnetic in nature, so it would seem that you’ve reasoned out your answer. I’ve never noticed this with my sterling jewelry, but I haven't tested it either. How odd…will have to try!
Answer:
It might be due to the presence of some other metal like Nickel, as far as I know nickel is a bit magnetic in nature.

But I'm not sure. You can try asking it to any of your local jewelers.