I have a hand held makita leaf blower that is billowing white smoke out the exhaust. I just changed the oil and it wasn't doing it before. I thought maybe I put a little too much oil (only holds 2.7 oz), so I changed it again, carefully measured the oil and it is still doing it. I put a new plug in it about a month ago. It still starts on the first pull. It's about 2 years old. What to do? It's 4 stroke.