If you have a hallicrafters S-40a, you may notice that stations do not tune in correctly, or it will not align properly unless the band spread knob is at 100. If this is the case then your band spread dial string is run incorrectly. When the band spread knob is at 0 the tuning cap plates for that should be fully open.
Sams, and hallicrafters manuals show something like this:
Yup the sams and hallicrafters diagrams are both wrong.
It needs to be run like this:
Here is a link to the corrected
sams.