I have a Ryobi 775R trimmer that I can't get to power up enough to run the trimmer and the attachments. I have changed gas, spark plug, carberator(got one from a friend that was discarding an old one), cleaned the filter, adjusted the carb, adjusted the idle speed. I am not sure what else to try. I see that there is a "sponge" like material inside of the gas tank. Is it possible that this gets clogged up and doesn't allow enough gas to pass through the plastic tubing and to get into the carberator? I'm just taking some stabs in the dark looking for ideas that I haven't tried yet. Thanks for any assistance.