I have a 4 year old echo trimmer model srm-210. It has ~500 hours on it. Gradually it has become harder to keep running when I switch from cold start to run over the past season, but would finally run after several tries. Then it would not run at all except in cold start mode. Did everything the manual suggested- no luck. Rebuilt the carb. and now it will not start at all! Acts like it is not getting any gas. Anybody have any ideas before I take it to the repair shop and spend $65.00? Very nice Web site, by the way.