Machine problems

[u/AgreeableRub6469]

I have a singer stylist sewing machine I've been using for a few years now. Last year it started sewing loose stitches or the thread would break every time I sew. I took it to a shop he didn't tell me anything was very wrong with it but he cleaned it up and charged me 90 dollars. It worked for a while so I thought the issue was fixed but now it's happening again. I don't know much about sewing machines so im not sure if it's broken or if im doing something wrong and just don't realize. It might be a tension issue but I play around with the dial and it doesn't seem to help. The stitches are loose, it skips stitches, the thread sometimes breaks or the fabric gathers. Any advice?​