I have heard of similar problems with these types of machines which is why I usually recommend that new sewers buy a used, basic, older machine. The newer machines tend to have more plastic parts which can lead to problems like you describe.
I would try and look for an older Elna, Viking, Bernina, Necchi and Singer machines that were built in the 50s or 60s.
These will be mostly if not all metal, have easy to use features and will require little maintenance. You may not have the speed control or have fancy stitches and monograms, but you will be less likely to tear your hair out with frustration.
