Chainsaw Repair

I removed everything required to do the vacuum test but I did not have enough hands to hold the saw, reach the impulse tube, pump in the air from the syringe and check for leaks at the same time. However, I did a very close inspection and saw no areas around the case gasket that could be leaking. I "orally" checked the I manifold and determined it held pressure (no leaks). Reassembled and still no fire. Spark looks good and strong. Questions...

Even if there is a pin hole leak somewhere in the case wouldn't it at least fire?
How can I "prime the thing" just to get it to fire once?
Do I add a bit of gas in the carb throat or in the plug hole? I just want to hear it fire once :-)
I'm willing to up-grade to the new carb and manifold Cut4fun suggested. Where to purchase?
If it was running before could the old carb/manifold really be the problem?