TURN-ONS AND TURN-OFFS IN CURRENT HOME ENTERTAINMENT RELEASES : Excellent Good Fair Poor : VIDEOCASSETTES

“Blues, Rags & Hollers--the Koerner, Ray & Glover Story.” Vermillion. $44.95. At two hours, this documentary probably tells most of us more than we want to know about the three Minnesota white kids who rudely stomped into the ‘60s folk scene with their rough country blues. There are lots of interviews and some recent performances, but lack of period footage hurts. Ultimately, nothing very interesting happens, and writer-director Tony Glover doesn’t discover a broad theme in such promising material as Dave Ray’s transition from hippie to insurance man and John Koerner’s from ramblin’ guy to amateur astronomer. But it’s thorough. Information: (612) 379-7281. 1/2