I also had a Tin Lizzie. Stitch regulation worked for about a year, then it worked occasionally and finally gave up the ghost. Dealer & TL were no help, so I just learned to work with the stitch regulator off. There were many things I liked about the machine, tension was very easy to set & maintain. It would sew with any thread.
As mentioned, make sure the sandwich is not too tight. Make sure the needle is in the right way and inserted all the way in. If it is consistently happening in one or two areas, make sure that the rails are very clean and don't have any dents or gauges in the plastic that the wheels ride on. That was the final straw for me. I could buy new plastic for the rails, but you had to take the entire frame apart to do so. I traded it in on a Handi Quilter.