Singer 237 Service And Repair Manual.
35 pages of great information.
Great diagrams!
Includes Parts list and diagram.
Here are just a few examples of what's included in this manual:
* Machine Lubrication
* Adjust presser foot height
* Time the Pendulum movement of needle bar
* Remove and replace needle bar.
* Remove and replace thread tension
* Set needle bar height
* Set feed dog
* Adjust thread clearance
Also has a page for Sewing Difficulties
"Hints for adjusters and mechanics".
Singer service manuals
manualsoncd.com
sewingwithsinger.com
sewingmachinemanuals.com