If its anything like cars, I suspect the end of the pickup tube is bare, its just cut off tubing. Most older stuff I've seen has a bunch of fine dust/dirt that sets in the bottom of the tank and any low places in the lines. The stuff has a very hard crust but is very fine, almost like ground dirt, base that never seems to go away.

I would give serious thought to replacing the tank and the line from the tank to the carb. Other wise expect to be cleaning that sediment bowl very often. The sediment bowl is more effective that modern fuel filters with this stuff, modern filters allow a lot of it to pass through and then it plugs up the passages in the carb. Gene