backplate and spraybar cleaning

I will assume it is off the engine and the reed is removed.  Remove the needle, but leave the spray bar in place, no need to mess with that

Soak in a jar of denatured alcohol or fuel overnight, use a toothbrush on it immediately on removal.  Flush the spraybar from both directions with a fuel syringe and clean fuel or denatured alcohol.  Then plug one end and make sure the hole in the spray bar is clear pushing fuel or alcohol and air through.

A pipe cleaner through the venturi is not a bad idea, just be gentle and careful of the reed seat.

Should be pretty good after that.  If it does not come all the way clean or fluid does not pass all the orifices then soak it again overnight or longer and clean it again.

Phil