I spent 5 weeks solving an extruder stopping part way through. The tension is easy to test. With the printer off pull the filament you should feel the stepper well stepping. If it feels like there is little resistance turn the knob that would unscrew normally this moves a nut toward the end of the bolt increasing the compression on the spring.
It will leave dents on the filament but not deform it.
Do you have a filament sensor? Does the filament run smoothly through it? This can also cause a feed issue. Is the sensor in line so the filament runs in and out in a straight line and does not make a hard corner? Also can cause issue.
Is the stepper on the extruder crazy hot during use? It will turn off if it over heats.
Is the filament path into the hot end free of obstruction? My sidewinder has a plastic guide with ptfe tube in it that was too short and not straight.
I actually had all of these at once. And a interment board connection loose so it dropped all power every once in a while.
It could be a number of things not just tension at the extruder. The sidewinder will print fine at the loosest and hardest settings. It slips on occasion on the loosest under extruding and tears the filament at the hardest leaving little filament bits behind.
My number one would be the filament sensor if there is on. You could just bypass it and see if that helps.