故障
こしょうする · koshousuru · JLPT N4 · noun
dislocation
🔧 故障 = obstacle (故) + hinder (障): something blocks the machine
故 here carries the sense of an incident or trouble, and 障 means to hinder or block, as in 障害 (obstacle). Together: a trouble that blocks normal working, i.e. a breakdown. Sound hook: koshou also sounds like 胡椒, pepper, so pepper in the gears.
故 — 古 (old) + 攵 (action/strike)
故 combines 古 'old' as the phonetic with 攵, a variant of 攴 meaning to strike or act. Originally it referred to a cause or reason behind an action. From this it extended to mean 'former, old, deceased' and 'therefore, hence' as a connector.