Do you have the stock tool bag? There should be a tool in there that looks like the digit "4," its a handcrank for this specific situation. If not, get a scrwdriver and a 3/8" 10mm shortwell socket and wrap either sandpaper/small cloth around the socket and jam it into the little hole w/ gears. I don't have the gvr4 for reference but I believe its behind the light resting on the headboard.