Before replacing anything, test!
How much pressure is at the carburetor? Gauge!
What is the orifice size of the fuel valve seat? Measure!
Is the fuel valve spring-loaded? Eyeball test!
Too easy to throw money with the only results the lightening of one's wallet.
Test first!
And
(F)riendly (L)ocal (A)uto (P)arts (S)tore
Jon