Genuine DeWalt part 871690 — a small conical steel spring used in the nose/hammer assembly to provide the correct preload for the retaining ball and related parts. It restores positive bit retention and reliable hammer action when the original spring has cracked, lost tension, or fallen out; an easy, low‑time repair that’s one of the common power tool parts to check when the chuck/hammer behavior is faulty.

Example models this spring is used with include DW514K, DW523K, DW557 and a broad range of older DeWalt hammer/drill series such as D25124K / D25333K / D25314K Type 2 and  D25324K.

This is the original DeWalt replacement spring (part number 871690) sold individually — check your model’s parts diagram for the spring’s exact location in the nose/tube assembly before installation.