Take the entire air filter Venturi assembly apart.    If you’ve never cleaned it thoroughly I’ll guarantee it is plugged up and causing your problems.  

I’m not 100% sure but I think you have to grind some rivets off and reassemble it with screws when you’re done.  
When you get it apart power wash the entire thing until you get unrestricted clean water coming through everywhere.   

Here’s an old thread about the same issue.    https://talk.newagtalk.com/forums/thread-view.asp?tid=427062&DisplayType=flat&setCookie=1 

There are after market fixes as well but cleaning the thing up so that it works correctly has allowed us to combine beans full days without air filter plugging.