Remove Old Cartridge and Clear Debris

What happens here

Once the bonnet nut is removed, use a pair of Knipex Cobra pliers (or similar adjustable pliers) to firmly grip and pull out the old shower cartridge. Be prepared for some residual water to gush out of the valve body as the cartridge is extracted; the towel placed earlier will be useful here. After the old cartridge is out, allow any trapped water or debris to fully drain from the valve housing. You can also briefly turn the main water supply on for a moment to flush out any remaining debris, but be ready to quickly shut it off again.

Goal: Extract the faulty cartridge and clean the valve housing of any debris.