I really like the Garmins GPS's apart from the BNC connector for the ariel. If yours connect with a BNC connector try replacing the connector with a new one first. Had to do mine twice now is 5 years because they eventually corrode. Found two models of BNC connector at £5, but one stripped down into lits of pieces and could be soldered in place, the other relied on screwing the cable in. Went for the soldered option and it works well.
Pete
-------------------- Sailing is hours of mild boredom with interrupted moments of sheer terror