Make garden work easier with this ergonomic and multifunctional Premium Spray Gun from Karcher. It's a comfortable size to grip and ergonomically designed with a Soft Grip handle to avoid fatigue over long periods of use - even when using only one hand. It also has an automatic lock feature that unlocks simply with one finger. It attaches via click connection, and is suitable for use with all established brands of garden hose.
This is Karcher spares reference: 2.645-047.0
This video should help with fitting this part. However, the exact layout and fitting technique may differ for your make and model.
Be safe - always unplug any appliance from the electricity supply before carrying out any work on it.
If you are in any doubt contact a qualified repairer.