I have several Pal injectors. I have one that has a dark blade in it, but otherwise looks mint. I ordered several of the Pal NOS blades on eBay, one pack at first then I grabbed the last cassettes. My first cassette won't eject a blade. My two other packs have arrived. I managed to replace the original blade, but it wasn't smooth as 50 year old crud was in the razor head. Should I replace the blade I just inserted?