ADDITIONAL INFO - I don't actually know if the tape I use is called Plumber's tape. I have three kinds of metal tape with adhesive backing: Copper 0.05 mm thick, 5 mm wide. Chrome 0.10 mm thick - some of it 5 mm wide, some of it 10 mm wide. I have experimented with placing tape in parallel with the tube, perpendicular to the tube (parallel with the opening), and angled. (I have also tried to post this on Flute Forum on Facebook, but I haven't gotten admin approval ... and I really want help! ) I know it is possible to widen the head joint's tube (or I guess just the part of the tube that is the tenon?). This will increase both the outer and the inner diameter of the tenon. Some flute makers believe that the change of the inner diameter might notably disturb the taper of the head joint. Given this belief, applying e.g. plumber's tape on the tenon might be useful in itself, and not just as a temporary measure before getting the tube widened. The tape increases the outer diameter of the tenon without changing the size or shape of the inner diameter. So far so good. But I get really frustrated using tape. No matter how thin, and no matter which angles I try, at some point - sooner rather than later - putting the head joint into the barrel results in bunched up tape. I have a (naive?) hope that instead of tape, something permanent could be applied to the tenon - some kind of thin plating? - without affecting the inner part of the tube. Does anyone have any knowledge about or experience with this kind of a solution? If so, please share. (PS - I don't know if this is relevant, but the head joint in question, which is "ergonomically altered" / "bent", has to be pulled out quite a bit more from my flute's barrel than is usual for tuning.)