Amperex Made in Holland 7062 – matched date codes. ULTRA RARE BUGLE BOY treble clef LOGO. Closely matched pair. Tube testers do not test for these problems in the manner in which you think, except to the extent that a tube tester with sensitive leakage detection will find far more “noisy” tubes than a tube tester with only “fair” leakage sensitivity, to the extent that the noise is due to this problem.