tvonics recorder - Help!!?

have 3 of these - have replaced power supply so far on one of them (common problem) but my daughters has stopped playing back recordings now - you select library and it shows the list of recordings - but the top left of the screen is blank where the date/time usually is - you play a recording and it stops playback after about 30 seconds (if that) - changed power supply in case it was that - have partly dismantled unit as full of 'fluff' still the same - any advice?

Brenda
October 2012