Has it been recently serviced? The bottom tension should not be terribly tight but should have some tension. I can adjust that but I can't tell you how to take that all apart and get it back together in working order. It likely could use a good cleaning. This is not an easy project for some one inexperienced. I would recommend taking it for service to someone who has worked on Elna machines. Before you haul it home sew with it long enough to be sure it is working the way you want it to work. Some times my Elna gets full of lint and nothing works right. That usually means the bobbin race has to come out to be thoroughly cleaned, oiled and tested/adjusted. I got my Elna back in 1975 to sew baby clothes. They are good machines if you keep them cleaned, oiled and adjusted and used regularly.
Motor. A lady brought over an Elna because she thought the foot control was bad. I tested it on another machine and it was fine. Looking inside at the motor, what I saw was blue flame shooting out of the motor. Cost wise it was cheaper for her to buy a different machine.