Sewing Machine %#$*+*@#$>&**

I have a Fashion Mate (252) by Singer at least 30 years old. What is causing the bobbin thread to jam up and I have to force/pull the fabric away from the plate far enough to get scissors under the fabric to cut the now many threads coming from the bobbin hole? I keep thinking it is the way the thread is rolled on the bobbin? My tension was set at the repair store last month when I took it in to have the bobbin plate fixed. that is all the repair man did in the 3 min I was there. show me how to insert the bobbin plate and he turned the tension to 5. If I forgot the mortgage and bought a $1300 new machine this would not be a problem.