The JE320 is an old deck that doesn't support MDLP. The N420D /only/ supports MDLP recording (via SonicStage) or fake SP, but it will of course playback normal SP discs (as you said, it plays the 74 minuter). Your discs are probably all in LP2 or LP4 and will thus play as silence on the deck (with track titles, and a time display, etc). Solutions? Redo all your discs using the deck and lovely old SP or redo them using fake SP. Or, better still, get a cheap MDLP deck, preferably with Type-S, for example: http://www.minidisc.org/part_Sony_MDS-JE480.html