OP here.
I used your suggestions and some I found on the internet as well.
I turned the couch over, and removed part of the fabric on the bottom. I discovered that 2 springs were broken. The springs were fashioned something like a Y with one end fastened to the couch and that was where it broke. So, I went to the hardware store, but couldn't find something I could screw the other part of the Y to the couch with. I had to nail it. Since 2 springs were broken, I bought 2 link lap repair circle thingies ( $.55 each) and 2 staple fence nails. ($.02) They are U shaped nails with points on each end. I put the circle thingies through the spring, and the staple nails through and nailed the springs to the frame. I also used 2 cable tie zip strips to join the repaired spring to the spring beside it that wasn't broken, for more support. I realize it isn't as solid a job as screws, but I'll keep my eye out for something that might work. This will do fine for now. I also bought a sheet of 1/4 " plywood cut into 2 pieces to fit under the cushions. ($11.99) I tried a thicker plywood but it was to firm, so I bought 1/4" knowing I could use both peices if I needed them. I did. When I placed them under the cushion, I realized the couch had sagged, leaving a gap between the couch and the plywood. So, I took a stitch ripper and carefully undid the stitches where the sag was. I stuffed some polyeyster fill quilt batten into where the sag was, and a little in the front to fill it out nicely. I sewed it up, and put duct tape around the edges of the plywood to protect the fabric. I used duct tape in a colour the same as the couch, in case someone should look, but that was just my touch. I'm very pleased with the results.