HELP! 572 idles bad and won’t rev up

[EFSM]

Should be all with the exception of the 570, 575xp and 576xp.

Reason I asked is that I looked at the 550 and 572 manuals and saw instructions on vacuum testing, but nothing very specific.
From my experience, the only failure of the pump diaphragm that will show up during pressure or vacuum testing is a crack in the actual large pumping area, which tends to happen on the Zama diaphragms after they swell and wear at the edge of the chamber. But if Husqvarna says otherwise…I’ll have to cut the flaps off a pump diaphragm to see if I’m right or not.

 

[Stump Shot]

Reason I asked is that I looked at the 550 and 572 manuals and saw instructions on vacuum testing, but nothing very specific. View attachment 484317
From my experience, the only failure of the pump diaphragm that will show up during pressure or vacuum testing is a crack in the actual large pumping area, which tends to happen on the Zama diaphragms after they swell and wear at the edge of the chamber. But if Husqvarna says otherwise…I’ll have to cut the flaps off a pump diaphragm to see if I’m right or not.

On a newish 550xp mkII that had run issues, the vacuum test failed and it was found to have a deformed flapper that wouldn't seal.