Small Engines (Lawn Mowers, etc.): Trimmer wont start, spark plug wet, little demon, oil mixture

Question
I have a Shindaiwa T-20 line trimmer.  I rebuilt the carb a few months ago, the gas/oil mixture is fresh, I've tested for spark and it's good.  The engine wouldn't start this weekend and when I removed the spark plug it was pretty wet.  I cleaned it and tried again, the engine would fire once or twice but not start.  I've removed and cleaned the spark plug more than 15 times and the same thing happens each time, it will fire a few times but after the 5th pull the plug is real wet again, and it never has started.  I've tried starting it with the air filter and the muffler off (the muffler is also pretty wet inside, but not plugged up) but no luck.  The only time is started and ran a bit was when I used straight gas (I only let it run about 5 seconds).

The mix I was using was between 32:1 and 40:1.  After the engine ran on the straight gas I diluted the mix a bit with some gas just in case I had accidentally mixed it too strong.  That didn't help.

Also, after the first time I saw the wet spark plug I stopped using the primer bulb, which you can see does have gas in it.

This has a Walbro diaphram carburetor.  I have it apart right now and would like to ask what, if anything, in this carb would allow this kind of flooding.  There is a section with a little cross shaped lever and spring device(underneath a diaphram with a metal piece in the center) that pushes a needle pin in a hole (with a seat?) but it seems to be operating freely.

I don't really know how this small little carburetor operates...is there a hidden check ball somewhere that could be sticking open?  I'm soaking it in gasoline right now, and I've also tried poking the thin wire from a tag into the small holes but most of the holes don't seem to go anywhere.

I'd appreciate any advice you could give me, even if you point me in an opposite direction.  But I'd really like to learn something about this little demon of a carb...it's had it's share of running problems.  

In the past this trimmer has had intermittent loss of power problems, like it runs out of power after I've been using it a while. I did find the port that leads into the muffler was partially plugged up and clearing that helped the power loss problem a lot.  And although it has been hard to start recently, this is the first time I haven't been able to get it to start at all.

John

Answer
Is the fuel brand new?  We find a lot of customers try and use their fuel from the last mowing season which is stale and will not burn.  

Have you checked the engine compression?  Is should be at least 90 psi to run correctly.  The manual says that 75 psi is enough but our experice has shown that the trimmer will have idling and power problems with this low of compression.

The T-20 and T-25 series trimmers are prone to low compression as compared to eailer models.  I can't count how many of these trimmers we have rebuilt...there have been too many...mostly in the late 90's.

When you check the compression make sure the engine is cold and hold the throttle wide open.  You will probably reach the max compression within 4 to 5 good pulls.

Let me know what the compression is.
Eric