I think I'm correct in remembering Expert Stylus used to service Decca cartridges, but only by sending them on to John Wright. Perhaps that's what they did with the Ikeda too.
BTW, back all the way to the OP: I have heard Decca cartridges make noises on slightly warped records, as they have very little clearance and occasionally the rear of the cartridge body can touch against a warped disk.