All these tips help
I love my singers 401A and FW..especially FW! a guide that works for you is essential.. the sites give such good advice.. until I got on them and adjusted, cleaned, oiled according to how I needed it to work I had some challenges with straight seems. I now use very light finger on material, guiding against a fewt thicknesses of tape and watching my foot placement, as I sew as fast as the machine will run..love it!
Wanted to try some of the new machines...the ones I have tried did not last and didn't make as nice a seam..but would be nice to have for labels etc.
Hope you find what works for you!!