Hi there, one of my sewing machines,which is just as basic a sewing machine you can buy has recently started being a bit awkward

, it keeps dropping stitches in both zigzag and straight stitch. After a while it also breaks the thread from the top bobbin. It doesnt seem to be a problem with either the thread or the tension and I tried different settings..
Has anyone else had similar problems and found a solution?
Thanks muchly
Tasha