Palmcorder blank playback

Hi, I've got a Panasonic PV-L750D-K vhs-c palmcorder which won't show video in playback. I get a black screen with a few white areas moving around, kind of like a tv channel with no reception. I've cleaned the heads with alcohol. I tried playing back a tape recorderd on my jvc super vhs-c but it's still blank. In camera mode everything acts like it's supposed to (ie. good pic quality, zoom, etc.). Any info would help. TIA!