Since the Ruixing is not documented AFAIK, and we have found no similar carburetor that is documented, I can't offer any suggestion other than the following:
- check for an air leak between carburetor and intake port: loose mounting, split rubber hose, etc;
- check for a crankcase air leak;
- check for other faults in the way it runs - or is it faultless except it won't idle?
- check that the fuel tank air vent is not stuck (loosen the tank cap and see if that makes a difference).
If it does everything properly except idle, and the above tests do not help, cleaning out the idle system with carburetor cleaner seems the only remaining step. I see no point in dismantling the diaphragms (metering or fuel pump) except as a way to access passages to blow out.
