carburetor speciallist required

i have followed tractor guy 's advice checked throttle spindle for wear seems ok engine still surging i think it must be the carburetor needs to be rebuilt does any one know of a speciallist they can recomend ? if i strip it down in the uk i wont be able to get the seals or any parts required i would be willing to send the carb to anywhere in the usa to have it rebuilt thanks rgds carlo