I have a lot of machines and I clean the ones I sew on the most twice a year. I take off the housing and oil, even the no oil ones. I clean with alcohol. The ones I don't use that often I clean once a year. I paid a repairman to show me how to remove the housing and clean my machines. That has saved me a lot of money over the years. I always waited for the warranty to run out first before doing my own cleaning.