pull start???

I have a blata 39cc midi quad. Its been stud for 1yr and the kids nagged me to get it going. I drained the tank, new fuel in, cleaned and checked the spark plug, removed the sponge filter of the air intake as it was soiled and after about 60 pulls it fired and what a lovely sound it was! I put all the ferring back on and nothing! It won't fire up. I have adjusted the rev cable at the top of the carb, asjusted the brass screw but nothing. My hands are now raw from trying and failing. What else can I do?