Once the rubber sleeve is damaged, the oil in the brake cylinder will be consumed quickly, and sometimes some small parts in the brake pump will rust after being eroded by rain, which will cause the brake cylinder to fail to return. So at this time, we just need to replace the damaged rubber sleeve with a new one.

2. Replace the faulty brake cylinder.

However, when other small parts in the brake system fail, these parts are still integrated with the brake pump. This will also lead to the situation that the brake cylinder does not return. So when this happens, it is necessary to replace the damaged brake cylinder with a new one.

3. Replace with new brake oil.

The brake cylinder does not return, probably because it has not been replaced with new brake oil for a long time. If the brake oil is not replaced in time, the brake will not return. So we just need to change a new brake oil.