Depending on the type of reel, baitcast or fixad spool, there could be numerous reasons for the noise Neil. If it is a baitcast style reel, you may have problems taking it apart, and re-assembling it, so I would take it to a tackle dealers and ask their advice, however if it is a "normal" fixed spool type reel, then you should be able to take the cover off, and give it a clean with WD40, then a light oil/lubrication, and put the cover back on, although it may just be the some dirt has got behind the spool, in whch case your problem may be resolved by simply removing the spool and giving the spindle, spool and spoolhousing a good clean.