The brass high speed jet located horizontally in the bottom center portion of the float chamber, way in back of the drain screw, is slightly clogged. Clean it carefully with a piece of single strand steel wire.
You would remove bolt #29 at the bottom of the carb to access the jet behind it: http://www.iboats.com/Carburetor/dm/...iew_id.1532321 . To begin with, try some carb spray, using the plastic nozzle. I wouldn't take the jet (#27) out -- brass (easily damaged).
Doesn't take much to cause blockages. Good idea to routinely disconnect the fuel hose after use, and run fuel out. It's not perfect, but helps some to keep the system clean. Old fuel turns to varnish, and clogs up small passages.
It's not hard to clean and rebuild that carb, when it comes to that. To do it, the carb is removed and largely disassembled -- some soaking and poking, finishing with some carb spray in every small opening you can find (good to discover how the spray moves through the carb too). Everybody has a favored technique for cleaning.
The carb comes off the motor -- would service it on your workbench. However, you should be able to remove the hex bolt with a box wrench, taking care not to drop it in the pan. (A magnet is a useful tool to have available.)
The brass plate that opens and closes is the choke plate, located in the throat of the carb. You can spray carb cleaner in both places, using the plastic wand that comes with a can of carb cleaner. Assuming you are not quite up to removing the carb, you might try the spray and see if it makes a difference.
next time it bogs try hand pumping
it goes you may have a bad fuel pump