" I think it sparked one time during a test but it may have been my imagination. "
The only way to make sure is stick it on your tongue like a 9 volt battery . Then run a magnet over the pick up . This is the only way to test it and know for sure . If you are bench testing it you WOULD KNOW . Tested one this weekend on a bench and it had a wick bad spark that left nothing to the imagination . It would actually jump about an inch gap to the plate . I'm sure you have looked at all the grounds , fuses , connections and checked continuity etc.