You don’t need to wait for a breakdown. Use the parts diagram to perform preventive maintenance:

The lower half of the exploded view details:

Common issue: The battery terminal block collects drywall dust. The diagram shows it is a separate item—do not clean it with metal tools; use compressed air.

The official Hilti diagram only lists genuine Hilti parts. But third-party alternatives exist:

| Component | OEM (Hilti) | Aftermarket | |-----------|-------------|--------------| | Hex chuck | $45 | $12 (generic) – Poor fit, ball bearings fail quickly | | Carbon brushes | N/A (brushless) | N/A | | Gearbox grease | $18/tube | $6 (moly grease) – Hilti #204 is unique; others cause slippage | | Trigger switch | $70 | $25 (universal) – Requires adapter harness |

Our advice: Buy OEM for the impact mechanism, motor, and control board. Aftermarket is acceptable for screws, dust covers, and rubber grips.

Before dissecting the diagram, it is crucial to understand the tool’s architecture. The Sid 4 A22 is divided into four primary assemblies:

The official parts diagram (typically found in Hilti’s spare parts catalog or through authorized service centers) presents these components in an exploded view—each part numbered and linked to a specific order code.