If you have a look on the MTWC website there is a full set of instructions detailing how to remove the rear wheel, brake drum, axle etc. including a great photo of what the brake should look like on page 14 of those instructions.

This set of instructions by Calum (Red Three on here) are freely available, as is a lot of other information for the M3W on the MTWC website. The MTWC website 5 Speeder section is always worth a look if you are not sure how to go about a job on your M3W, there is a lot of info there. https://www.mtwc.co.uk/wp-content/uploads/2018/01/M3W-Rear-Hub-and-Sprocket.compressed.pdf