[Benson]

1. If you are closing the idle air screw (gently ... the screw is only brass, whether plated or not and deforms easily).

2 Then blowing in idle jet to test idle air screw seat you MUST at the same time also plug the idle mixture port inside the throat with your finger.


3. If it still leaks then the idle mixture needle is too short or the spring on the needle is too long and collapsing before it seats.

To test for condition 3: Remove the spring and "cap" if it has one and put the idle air screw back in before testing again.

Look for the coils of the spring touching each other. A shorter spring will fix this.

Also maybe some one drilled out the seat larger than the needle diameter.