The machine most likely needs a thorough cleaning and lubrication. Old oil gums up, some times the gears are greased and the old grease gets hard, and then it doesn't want to run.
Remove the top and the front piece and the bottom cover and clean, clean, clean, clean.
If it moves, should move, looks like it should or might move, clean it. Especially all the gears. Make sure the machine is lint free too.
Then oil everything that moves, should move, looks like it should or might move. If the gears had grease on them then that's a toughy. Some say to grease the plastic gears, some say never ever grease plastic gears. All I know is every Singer I've had with plastic gears had some kind of white grease on them, and Singer sells a white grease for gears.
I either use the white Singer grease, or Tri-Flow synthetic grease. I think the T-F is better.
So, that's where I'd start.
Joe