Firstly Walbro have service manuals and videos all readily available on line
http://www.walbro.com/parts-services/
You just have to make the effort to scroll to the bottom left corner of the screen for the links.
Next all cube carbs work the same, there are only 2 kinds rotary valve & butterfly so if your EXACT CARB is not mentioned right down to the last digit, it does not matter they all WORK THE SAME.
Next you really have to clean them out properly and that requires more than a soak in simple green overnight a a few blasts of carb cleaner.
On the subject of carb cleaner, most of them destroy the seals in cube carbs which s why Walbro floggs their own formula.
Then cube carbs are really really really really really really really hard to clean if they are full of stale fuel tars & varnishes.
Some have needed better than 20 hours of ultrasound in solvent to finally clear them.
Next the primer is actually a PURGE valve and it sucks the air first then the fuel OUT of the carb and returns into the fuel tank.
The carb has 2 to 4 one way valves in it and the purge VALVE also has a one way valve in it, thus it only works one way.
Hook it up so it sucks against a valve that closes under vacuum will not work so the bulb rill not return , even if the valve in it is clean & working properly.
Back a few days ago Boo posted a link called Carb info or some thing like that.
It goes to a Pommie web site with the most boring presenter ever on the web but if you can stay awake through a couple of his 1 hour long presentations you will have all the knowledge needed to tackle the job with confidence & understanding.
Sorry, no gen X,Y,Z instant 10 second fix.