It never fails, you're in the middle of an importatant project with the deadline near and uugghh, your machine quits. After all --- it's Murphy's Law --- your machine will break when you need it the most. If you're lucky, you have a backup machine to use while you cart yours off to the repair shop to await service.
There are some things you can do to try to prevent this scenario. Taking good care of your machine is very important and proper maintenance can keep you up and running. You should take your machine to your service man every six months to a year to be cleaned, inspected and lubricated. Although the cleaning and lubrication are important, the inspection is crucial. Very often, the service/repair man can tell when something is worn and it can be fixed or replaced before it goes out! This saves you precious sewing time.
You should also be doing some maintenance of your own . It is important to keep your machine clean, especially in and around the bobbin where the lint likes to hide. Try to avoid blowing with your mouth to remove the lint. When you blow with your mouth you can actually blow moisture (saliva) into this delicate area of your machine. You don't have to worry about your machine catching your cold but you do not want to take the risk of even the slightest bit of rust forming. If you absolutely have to blow.......use canned air. It is, however, better to vacuum the dust and lint out of the machine rather than just blow it around inside your machine.
One of the best investments I ever made was buying the small attachments for my vacuum cleaner. The attachments are made to clean electronics including sewing machines and computer keyboards. These attachments get the lint out and clean the tightest and tiniest of spaces. They are well worth the money, usually under $25.00 for the set. You can purchase them from quilt shops, office supply stores and some big box department stores.
Know your machine. Read the manual and follow its directions for regular maintenance and cleaning. If your machine requires you to lubricate it, do so regularly. Learn how to thread your machine properly and wind bobbins evenly. It also pays to use fresh thread and change the needles so you are always working with a good point.
I think it is also important to find a service man that you can trust. Sewing machines are a big investment and you need to be able to work with and trust your technician to ensure your machines are in good working order and when they do need service that they are down for a minimal amount of time.
A little TLC will help keep your machine humming happily for many years of creative quilting!!!