Cock — Amateur

: If a balance wheel stops moving when the cock is tightened, it may be due to insufficient vertical clearance (endshake). Some amateurs resolve this by "shimming"—placing a tiny piece of paper or metal foil between the cock and the mainplate to raise it slightly.

: The balance cock also holds the "stud" (the fixed end of the hairspring). Ensuring the hairspring is flat and centered under the cock is essential for accurate timekeeping. Types of Cocks in Watchmaking amateur cock

For those interested in the artistic side, historical watches often featured highly decorative, hand-engraved balance cocks (sometimes called "watch cocks"), which are now prized by collectors as miniature works of art. How to fix balance wheel movement issue? - Facebook : If a balance wheel stops moving when