2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/12786Using the novel data set of the MACHO project, we show that three ``Blazhko Effect'' RR Lyrae stars show nearly-pure amplitude modulation of a single pulsation mode. This is strong observational evidence that the ``Oblique Pulsator Model'' is the correct solution to this 90-year-old problem.31 pages, 9 Encapsulated PostScript figures. Submitted to the Astrophysical JournalAstrophysicstext