How do calibrate my guitar hero guitar?

I have had Guitar Hero World Tour for Wii for a while now but I am only just experiencing problems with this. The guitar has been lagging but not the usual audio/visual lag (I have tried to recalibrate this many times). When I strum it takes a while for it to strum on the game. For example, I'll strum the first note on a song I've beaten many times but it won't show up on the game until long after the note has passed. can anyone help?