Muv's videos are easy to follow. If you are able to sew and follow directions you can do this. If you have a manual you can do this. UM If I can do this you can too..... That one looks just like the one I am working on this week. Mine has a twisted out of place needle bar to turn. Does yours actually stitch? If it will stitch it isn't very hard to clean them up. The bobbin area just has a couple clamp things that you move and the shuttle will pop out and you can clean it up. To re assemble just look in the manual - I'm so glad there are only 2 parts and they are EASY to do. As long as it works all you need is to clean the tension like Muv does in the video! A bit of cleaning and oil and you might just be good to go. Here is a repair manual. It even tells how to fix the motor.
http://parts.singerco.com/IPinstManuals/15-91.pdf Here is a post with Muv's videos.
http://www.quiltingboard.com/t-155695-1.htm at the top of Utube there is a button to hit and you can see all 9 of Muv's videos. You don't need to do the motor if it sounds good. The wires need to be inspected for cracks and bare wires. Sew-classic has info and wires to buy. She also has parts. You really don't have anything to lose by trying to clean it.