carb is off a 2000 trx 400ex ---- first timer, walking through the manual. I took off the air cut off valve and it says" apply vacuum to port. the vacuum should be maintained. air should not flow through the valve ports when vacuum is applied and should flow when vacuum is not applied." I checked this by sucking and blowing into the vacuum port, air didn't flow either way. is this part clogged or should it be tested another way? do i soak this plastic part? thanks for your input.:icon_question: