I need help from any featherweight 221 owners. I am now the proud owner of one and I have a question concerning lubricating the motor. The original manual says to use the lubricant when needed to keep the motor running smoothly. Now I read online that you should never lubricate the motor because it will sieze or stop. That you should leave it alone. I really don't know what to do. Singer still sells the little tubes. Why would they sell it if you are not supposed to use it? Please help, I don't want to ruin it.