I am seeking a cover for a pickup in a vintage American P Bass (c. 1958). It has a post factory mod. pickup added. The pickup has no notation on it at all, but looks exactly like a Jazz pickup, and I ordered a set of authentic Fender Jazz pickup covers for it, but they do not quite fit - the cover goes over the pickup, but the holes in the top do not align exactly. Are there slightly different models of Jazz pickups? Are there other pickups that look just like the Jazz?