OK, finally figured this out, I didn't realize before, but there are 4 additional screws on the inside that allow removal of the entire front of the device which includes the clear plastic window covering the lcd. Once I got that off the dust was easily cleared from the lcd and the clear 'window'.
So,
take the 4 screws out of the back, remove the battery(may not be necessary, can't remember), locate and remove the 4 TINY screws holding the face plate. clean, replace, enjoy your crystal clear display!