Check the little float window at the front of the carb (a small dentist style mirror is ideal for this) and check that the fuel level is on or slightly above the centre of the window. If it's too low then the blockege is before the carb (i.e. it's not comming in), if the level is way too high then the float is sticking. If the level is pretty much bang on the money then the blockage is down-stream within the jets of the carb itself.
Usually a small amount of fuel-cleaner and a good long run down the motorway (100miles or so) will give it a good clear-out and draw the crap (if there is any) out of the jets and float chamber, burn em up and blow em out the back. It does all cars good to have a good run out on the motorway every so often. It certainly does my ma12 good.
(Y)
