Still being somewhat of a newbie, have a situation that has come up a number of times. Have taken various stepper units apart on different machines, then cleaned all the gunk out, and NOT added any lube. Most of the time the stepper works fine, and the coil spring always seems to work well at the proper tension. But in a few cases, the stepper still didn't work properly and usually because it seemed the smaller tension springs just weren't strong enough, even though the unit was completely clean and otherwise moved freely.
In these cases, is it just old springs that have lost some pulling power? Is shortening the spring, which I have done a few times, criminal behavior? Should the springs be replaced with new? Or is it something I am missing in diagnosing the problem?