Hi, I'm pretty new to this hobby, but I do have some experience with the AP Wasp. Broke in my second one last week and its been flying as good as the first with no problems. So, here's my 2 cents in case it helps you.

Would have guessed that you had an obstructed needle valve assembley, but seems that's been ruled out.

When my Wasps act as you describe, I'll usually over prime - up to where I can hear a slight squish when I turn the prop over slowly. If you connect the starter battery at this stage, you'll see smoke being scavenged out the muffler. I'll turn the prop slowly until I feel a slight jerk, or even better, a definite kick. (In the latter case, I know that everything's perfect and it'll start first flick.) Sometimes, if I'm sure it's not hydrolocked, I'll just proceed to the next step even if I don't feel a jerk.

Then I hook up the starter battery and flick the prop. If you've over primed, the engine should not start, but at least you'll hear a pop. If so, keeping flicking away and pretty soon, the engine will burst into life. If there's no pop, then its probably still flooded - a few quick flicks or just turning the prop over a dozen times will get it popping)

I used to try for the perfect prime (i.e. start on first flick). In time, my percentage increased, but on the field, when I just want to get in the air, I've often found it much much easier and quicker just to do the process described above. Incidentally, my first few attempts took as much an hour to get the engine going (newbie working alone!) but that soon became a matter of a few minutes.

btw, I start my Wasp with a homemade heater powered by a 1.2V AA NiMH battery - a full charge will last me more than a couple of days' flying easily. Think that extends my plug life a little. If you can feel the kick or hear the pop, then I think you're getting enough voltage and the plug is ok. Haven't had any probelms on either of my 2 Wasps.

Oh, and just after I got my second Wasp, I tried using a starter - it's even easier, and overpriming it slightly as described above will get the engine running almost on contact. I use a full size starter and just touch the cone to the prop - it doesn't grip very well and will slip if the engine is flooded, but otherwise, flicks the prop just enough to get things going quickly. A stick is still faster, but the starter is more consistently easy.

One last thing about the Wasp - I've found them to be pretty decent engines at a great price, but the QC is lousy - check every screw and fitting before sending it up in the air. Had to tighten the carb screws on my first one and my second needed the cracnkcase bolts tightened. In both cases, I experienced an air leak while breaking them in on the bench.

Oh, and if you're changing the glow plug, you could try the Norvel freedom plug - it will fit, but you'll have to change the head as well. Bought and test fited both onto my Wasp, but haven't tried running it with them yet. I think the quality and perhaps availibility of the Norvel product might be a little better.