I had this same problem on my '55 first series. The sending unit is all steel tubing. Mine looked like a piece of round stock when I removed it. I used carb cleaner and a coat hanger wire to clean it out, then used compressed air. I removed the gas tank, and it had literally 5 gallons of sand a sludge in it. Then I took it and had it boiled out at a radiator shop. I put a 5/16 in line fuel filter in the fuel line before the fuel pump. Which is a good idea on any vehicle you are just starting to get running. That way, if I starved for fuel, I removed the filter, tapped out the junk in the inlet, put in back in and drove away!

Bryan Bauman