String Trimmers

Hi, I have a Husqvarna 128 LD string trimmer, model #952711953 and I've got some white smoke puffing out of it when I turn it on. I've mixed fresh gas and oil and that didn't seem to do the trick. I've taken it apart to try to clean what I could find, but quite frankly, I don't know exactly what I'm looking for and what to clean/fix. It has no problem starting. If anyone has some insight as to how to troubleshoot this, all would be appreciated. My lawn needs some major trimming around the edges! Thanks.