help me find an electrical gremlin, please

One will work on both and only one will work with the five pin. I can't remember which way it is. Do you have a two prong ballast or four prong.

If two prong then I think the four will work. If four pin then I think you need the five pin.

Maybe Del will confirm.

I am still curious why you have no AC voltage coming from the pickup. In the past I have read on here that some have gone through two or three before they got a good one.