I have had a basic Tin Lizzie for several years. My dad also has one. Between the two of us, we have had our share of problems. It is very picky about what thread you use on top. I have found that it likes Glide thread and I have less thread breakage with it. Less, but still sometimes a problem. I have had tension problems for a couple of years but if I only use glide thread, there are very few spider webs on the back. My machine has also had a problem in recent years with racing when it gets warmed up. When I have been quilting for a while, stop for a minute and restart, it stitches a hundred miles an hour for a few seconds, often breaking the thread. I called customer service and they referred me to a repairman who had to call them. They told him to have me spray canned air on the circuit board. This was a great temporary fix but it has started doing it again.
My dad's machine has tension and thread breakage problems. Also, he is having trouble with his circuit board. He ordered a new one and tried to replace it himself. They sent the wrong one so he is waiting for them to send another.
There are very few people around that repair them. I live in Atlanta area and have to have someone come from Tennessee.
I realize that the machines are much less expensive and you get what you pay. My husband bought me this machine to do quilts for others but it has not proven to be reliable enough to do that but it has been helpful to quilt my own quilts.
Also, our machines are nearly 10 years old and their quality might have improved since then.