i would start with cleaning the filters, take off the carb, disassemble it as much as you dare, and give it a good spray/soak with carb cleaner. if i would make any adjustments, i would lean it out a little, because in hot weather, the air is less dense than cold winter air, so in summer it's getting a slightly richer mixture. but before you start messing with the settings, try cleaning it first, because if it hasn't been started in a while, you don't know what's gummed up and not working properly.
or my solution would be to get a Stihl.
i don't use mine frequently, but it ALWAYS starts, old gas, new gas, whatever. i never buy anything other than regular gas either, and i never buy 2-cycle mix. 10w-30 in gas and chain lube. every once in a while i'll put in a little marvel mystery oil or seafoam. my saw only stopped working once, i took off the carb, disassembled, cleaned, reassembled, and it was good as new.
tmm