What is the test for establishing that a breathalyzer device is in proper working order?

People v. Gower, 42 N.Y.2d 117, 397 N.Y.S.2d 368, 366 N.E.2d 69 does not establish a contrary rule, despite its suggestion that it might be appropriate to shift the emphasis in such matters from "technical issues of admissibility of evidence to means for measuring its persuasive weight" ( id., pp. 121-122, 397 N.Y.S.2d 368, 366 N.E.2d 69). We reserved decision in that case on the question presented here, namely, "whether or to what degree the People, in laying a foundation for admission of the results of individual tests, would have to establish that the breathalyzer device was in proper working order" ( id., p. 122, 397 N.Y.S.2d 368, 366 N.E.2d 69).