Oh, she's pretty! Have you looked her number up yet to see when she was born?
http://www.ismacs.net/singer_sewing_...-database.html As for her not being the best, I find that I'm afraid of hurting the prettier machines, so am perfectly happy with a well-loved one because I will use them rather than just putting them out to look at.
You can get the bobbins from
http://shop.sew-classic.com/Bobbins-...-SCBN45785.htm for a good price. (I am not affiliated with this shop in any way, other than it has great prices and I shop there often.)
What type of issues are you having? I always look at the threading. Is my needle new? Is the bobbin in correctly? Is my thread the appropriate size for the fabric? Then I look at the tension before thinking it's something more serious. Look on this page -
http://www.ismacs.net/singer_sewing_...s-200-299.html and download the manual for the 221 class. There is a tension assembly picture in there that will tell you exactly how to put the tensioner back together if you decide to take it apart and clean it.