The pin indicated on the Detent or Setting Lever, No. 30, wears off through the constant pull it exerts, causing possible loss of the Stem and Crown. The Setting Bridge, No.31, holds both the Detent and Minute Wheel in place. It is shown with a spring broken because of constant pulling of the Stem.

The Regulator, No.33, controls the rate of the Hairspring, causing the watch to run faster or slower as desired.  Should the pins which hold it become damaged, they must be repaired. 

A defective Clutch Lever, No. 32, caused the winding mechanism to lose control of the setting and winding of a watch.

The Hands, No. 34, indicate the time. Obviously, they must remain firm and tight, and must be so adjusted that they will not rub against the crystal, and lose time. The Mainspring, No.35, is the engine of a watch.  Only a perfect Mainspring will enable a watch to keep perfect time. A cheap Mainspring may not break; it is too soft.  But it will not enable the watch to run properly. Inferior steel, as used in the manufacture of poor Mainsprings, is not properly tempered causing the spring to “set”, as shown by No. 37. In the condition, no power is left to drive the escape train.

A broken Mainspring, No. 36, one with a damaged outer end, No.37, or inner end, No. 38, will cause a watch to stop at once.  A new Mainspring must be installed