Sir . . . . . Jim VEWY . . . common on those, along with 5-Useless -4's from the 50's. Pretty high filament current passes thru those units and the solder in the pins connecting to the bare copper wire within it crystallizes, then finally makes poor enough interconnect on the decreased conductive surface area to be intermittent. BEE-4 you condemn it . . . note that the hole in the tip of each pin is swaged down in size fron the acuual internal diameter of the inside of the pin. Sooooo take a small mill file and work on that tip end of the filament pins to get the opening up larger to then ease the flowing in of fresh "sarter" inside, while ye olde iron heats up the outside side of the pin. Finally re use the file to dress down the shape of the pins , in case adhering solder increased its effective side diameter, or that you were left with a blob on the pins tip end. Me thinks that action will then restore your 5Y3, probably, for a whole 'nother lebenteen years ! FWIW . . . . I even have a special crimping tool that was made to ease the performance of that solder inflow by its cutting a thin slot down the side of the pin. Of course nowadays one could equally use the very sided of a #411 carbide cut off wheel . . . in a Dremel tool , then run longitudinally along the tip of each of the the tubes FILAMENT pins. 73's de Edd

::You would think a 5Y3 is either good or bad, but I just had one to fade out after 10 or 15 minutes playing. Quite strange!
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