How can I fix my Husqvarna 254XP chain saw?

My Husqvarna 254XP has always been difficult to start despite an overhaul and its getting worse. Ignition seems fine. It floods after several pulls and you eventually end up with an exhaust full of fuel. It may take all day to get it going. Tune the carb, use the machine, put it away for months, take it out and back to square one. It sometimes starts if you empty the tank but soon runs out and will not restart on refilling. At the moment I can not start it at all. Is it worth buying a new carb? Are they temperamental? Reluctant to waste more money.