Interesting about the ships. I didn't know that but as Strangeways has said if the relay drops out as soon as power is turned off then its not a residual magnetic problem. Just a thought but could the tape be holding the contact plate up enough to allow the the score contact to activate but is not allowing the hold in/latching contact to close. I don't have a wiring diagram and are assuming the score and latching contacts are separate contacts on the same relay? I would try putting some paper or similar between the latching contact only to see if that has the same affect as the tape.
