I have a HR214 that is likely 30 years old. It has been a beast (I personally have used it for 15 years). This season, it began smoking quite a bit (coming from the engine, not the exhaust) after about 30 minutes of use. It also seems to be losing power. I have changed out the oil and checked the air filter. Are there any gaskets or seals that likely need to be replaced, and can these be done by a non-professional.