My repairman told me to bet the little vacumne tools and told me exactly what to do take apart to clean it, exactly where to oil, etc. Whenever I run into trouble I call him (always ask for him... there are four repairman there) and he starts asking questions....
Did you.....? Is the............? by the 5th or so question he has pin pointed my problem. Oh, I'm in love with my repairman. The last time I took in my machine he looked at a couple of thing, sold me a new bobbin case and gave me a couple of suggestions. No more problem. And he didn't charge! My husband was impressed, too.
I use my machine very hard and I need advice/help with it two or three times a year. So far, so good!