I have a full set of old gut strings that came off one of our vintage plywood basses. These strings maybe from the 1950s for all I know. The G & D are varnished and the A & E are silver wound (very tarnished) with purple winding top and bottom the really unique thing is the end with the knot had a black rubber washer that says golden and then a leather disk behind the washer. The strings are thick and look to be in good shape. I have read threads on TB that say oil the old gut strings with mineral oil and re-install them, but what is recommend to clean the A & E string (the E string is massive) to re-use them. Also how do you know when a set of old gut strings are past their prime and need to be retired? The little disk of leather at the tail piece end of the string threw me maybe it was a home remedy for a vibration or the slots on the tail piece were too big for the knot on the gut string. If anyone knows what kind of strings these might be chime in and are they worth re-installing also I think I read Gamut will re-wind strings (A & E?) it that any string or just their strings?