In the long saga of getting original 1960s Apollo spacecraft communication hardware working (parts 1 , 2, 3, 4, 5, 6, and 7), the latest challenge was posed by a ground test receiver which the intrepid reverse engineers discovered had been modified after its Apollo days for use in another (unidentified) project. Restoring it to its original specifications involves a deep dive into the details of crystal frequency standards, aided by the fortuitous discovery of the “missing manual” for the equipment, contributed by another collector.