Can you tell me if these pickups are already sealed or not? I always thought that they weren't and the pickup cover is removable, but I just received a set from a ebay seller and they are already sealed. Is there a way to remove the sealing material? They look like hardened hot glue to me, may be I can melt them away with a soldering iron? I want to remover the black pickup cover because I'm planning to make a custom wood cover for them.