Good thing you asked, Sewnoma, I was pondering this question last night when nothing I could do to tension seemed to help. This is another of the major parameters in mechanical sewing that hasn't changed in like a 150 years. All machines have pressure regulation, all manuals state it as a an important feature that has to be right - then you're on your own. Nothing about which problems are caused by to much or to little, on how to figure out where to start, not even how to zero out and start over. The "clockwise is more, counterclockwise is less" is almost insulting.
I got this beautiful old high arm treadle that I cleaned and massaged into action, but couldn't figure out why the pressure rod adjustment screw wouldn't thaw like the rest - it looked clean. Turned out it was bottomed out so tight I just thought it was stuck. The ca. 1890 user manual I found online says the same about pressure as they said in The 1950's and probably to this day - "get it right or else". Didn't do 125 years worth of previous owners much good.
Mechanical machines, no matter how good, cannot sense what is happening, only respond to user antics. Does anyone know how high end computerized machines are set up? Do they have sensors on feed and actual stitch length and quality? Do they have automatic pressure regulation?
It's ok if you want to be anonymous about knowing anything about electronic machines🤐
Stein