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Symbol D.N.—erratic agitation of the needle which covers less than a quarter
of an inch of the E-meter dial and tends to be persistent. (HCOB 8 Nov 62)
- ragged, jerky, ticking needle, not sweeping. (HCOB 15 May 69)
- a dirty needle is any needle which departs from the appearance of a clean needle. (SH Spec 224, 6212C13)
- a dirty needle is only a little, tiny persistent rock slam. (SH Spec 184, 6208C14)
- one that jerks, tips, dances, halts, is stuck or has any random action on it with the auditor sitting looking at it doing nothing. (HCOB 30 Dec 62)