If it's original the only filter is in the carb. Hold the big fitting on the carb with a wrench and loosen the metal fuel line going to it. Then remove the large fitting that holds the filter in the carb. Pull out and replace the filter, reassemble. If you don't use 2 wrenches to seperate the line from the fitting you can kink the metal line. I've never used any kind of sealer on the threads before, and have never had one leak.