Okay, being a little frustrated with this, I went out to do a little trouble shooting... I noticed the Zama carb from my 351 (parts saw - completely unassembled) looked very much like the Walbro on my 357... So I pulled the carb and the first thing I noticed was the makeshift gasket someone put between the carb and intake, also it completly blocked the impulse hole at the bottome of the carb. I already had the Zama carb with the air-cleaner assy. and throttle linkage/choke assembled, so I installed the Zama from my 351 on the 357. The saw started and idled as it should right away, but seemed to die off when hitting anything past mid range rpms, I'm assuming due to the lack of fuel delivery from the 351 carb. Anyhow, I reinstalled the Walbro, minus the defective gasket, the saw started and ran great, idled and reved as it should, for about 20 seconds, then died and wouldn't start again. I have read some threads along the line of the defective Walbro carb, some with the link to the service notice. I'm considering calling and getting a price on the Zama replacement from my local saw shop, trying that, and if that doesn't work, handing the saw over to them along with my troubles...