Husqvarna 50 Workshop Manual page 37

Test the fuel inlet lever, spring, needle valve and seat
condition. Connect the pressure gauge P/N 5025038-01
to fuel inlet fitting on the carburetor. Immerse the
carburetor in a suitable container of fuel. Pressurize the
carburetor to 50 kPa (7.2 psi). No air leakage is
permitted.
If air leakage is observed, remove the screw retaining
inlet lever pivot shaft and carefully remove the lever
shaft, spring and needle valve.
Check the needle valve. Replace a damaged or worn
needle valve.
necessitate the installation of a new carburetor.
Make sure the work area is clean and exercise
extreme care during disassembly, cleaning and
reassembly of the carburetor.
Remove the screws retaining the metering diaphragm
cover and remove the cover. Carefully remove the
metering diaphragm and gasket.