You will notice over time your brake efficiency will start to decrease. The same amount of brake lever travel (how much you squeeze the lever) will result in the scooter not stopping as quickly. We can see in the next picture the lever has travelled a long way towards the flame grips (if your scooter did not come with flame grips, please consult your dealer ) before any actual braking has occurred. This results in your scooter taking longer to stop, and more dangerous scooting... This means your brakes need adjusting back to normal operation.
As a brief explanation as to why this occurs I will give a very quick outline of drum brakes. Basically you have a round cylinder which your braking system sits inside. This is called the drum.
You have two round metal pieces which have the braking material attached to them called the shoes. In the yellow circled area you will notice the almost vertical bar which I will call the actuator (couldn't find proper term) which when at rest is almost touching the shoes. This will be important later on.
The red circled areas are your braking material (note this is the black part of the shoe, and not the metal piece). Over time this material will be rubbed off when causing friction during the braking process. At some point, too much material will be rubbed off and your brake shoes will need replacing. Your friendly scooter mechanic should check your brakes during regular servicing and will advise you when your shoes need replacing. (This is also the reason you get black dust on your car wheels. Your brakes are doing work and the braking material is causing friction and rubbing off the brakes falling down onto your wheels and making them look yucky and dirty)
When you squeeze the lever, the shoes are forced outwards towards the drum. You will notice the actuator is a lot less vertical this time and putting outward pressure on the shoes. The braking material contacts and places friction on the drum and slows the scooter down. Over time, the braking material is ground off and worn down. This results in there being a greater space between the shoe and drum, resulting in less braking occurring. Now we must adjust the brake shoes to be closer to the drums to compensate for braking material wear. To do this, we cause the shoe actuator (flat metal bar doodad) to be less vertical at rest which pushes the shoes out more at rest, thus decreasing the distance the shoes must travel to contact the drum when we squeeze the lever.
If you look at the front wheel, you will see the following assembly coming off the axle. This is the adjusting assembly for the brakes. The rear brakes have a very similar adjusting assembly. You will notice the hump in the adjuster I have highlighted with yellow. When you adjust the brakes you are rotating this adjuster between the humps. So it will not be a smooth rotation like a normal nut. It will rise and fall in time with the humps in the adjusting nut. At the moment because the dip is showing, I am half-way through one adjustment. The "dip" will sit vertically and you will feel the adjuster fall off the "hill" and easily rotate around to sit on the dip.
On the 2003 Milan, you will require a 14 mm spanner. When you are adjusting the nut you will want to rotate the nut clock-wise as if you were looking at it from the rear of the scooter (basically from the ground up). This will force the braking assembly to cause the actuator to be less vertical in the rest position, and hence push the shoes out a little further.
Now here comes the personal feely bit. I like my brakes to be almost on straight away and the lever to start operating the brakes almost straight away. Less lever travel results in braking happening at an earlier stage, means slowing down quicker.
It is a matter of adjusting the nut one bump, spin the wheel (you will need to sit the scooter body up on something to hold the front wheel off the ground or if you are strong enough, lift the scooter by the axle nut), and pump the brake. This helps settle the actuator and shoes in the new position. You will want to spin the wheel again to make sure the wheel is not binding. The front wheel should rotate easily, perhaps almost 3 revolutions. If you turn the adjusting nut too many times, the wheel will come to a stop almost straight away. This means the shoes are touching the drum all the time and you will be grinding off braking material as you are riding. You will wear out your shoes faster, which is costly and perhaps put a bit of extra strain on the engine and clutch so you want to get the adjustment correct.
The rear wheel adjusts in exactly the same way as the front wheel. It is already off the ground thanks to the centre stand. One thing to note about the the rear wheel is that is also driving the rear gears at the same time, so it does not rotate as freely as the front wheel. It should spin about 1 rotations or so. Adjust the nut one bump, spin the wheel and pump the brake. Then spin again. If the wheel rotates fairly freely and the lever position is comfortable and operating the brakes in a position you like, then you are done.
Once you think you are happy with the adjustment, pop the scooter off the centre stand and push it around a little and test both brakes. If all feels normal, start the engine and do some small slow-speed braking tests in an open area. If all feels normal pat yourself on the back and go for a scoot with your newly adjusted brakes...
If you have any reservations, please understand that braking is critical to safe scootering and pop into your local friendly scooter shop for a reminder course on brake adjusting. Alternatively ask a question in the comments section and I will endeavour to answer it. I was thinking about doing a video of the adjustment procedure as well. If people were interested in that, pop it in a comment.