These carbs are so simple that I would take it apart & clean it out. I have a 49 1/2 ton with original tank too. I have 2 of those glass filters in the fuel line. One right at the tank and one right at the carb. The one under the tank got gunked up weekly for about 2 months. Now I clean it about once a month. I still get a little bit at the carb filter which tells me some gets in the carb. I took the top off the carb & sure enough, there was some gunk in the bowl but it was running fine. So, if I have 2 filters and still getting gunk all the way to the carb then maybe you should at least take the air horn off & peek inside to see if the carb bowl is dirty. My2¢ Good Luck