HELP!!! with 1971 HC

[Dave1300GLS]

Hi chaps i was just givin my HC a service at the weekend and as a last bit of my exercise i shot some carb cleaner into the intake of the carb after that i noticed the car would not rev, well it did rev but only to 4000 rev foot to the board and when i drove it back to my house the maximum speed i could get was 35mph. the carb is the early stromberg unit with the round air filter and the adjuster screw underneath. it seems to me like the main jet must have some *Bleep* in it as i am more a zenith 301Z expert would you say my asumption is sound or could it be a split diaphram or do they have a part that regularly fails i just want a few pointers before i start stripping.

Cheers
Dave.B HC82

[Pork Pie]

check the diaphram lad, it may of slipped off its seat or split,if you need one just shout and i`ll post you one up asap.