There are foreign objects inside the bell and oil stains on the surface of the bell.

1. There are foreign objects in the bell: after the vegetable delivery bell is used for a period of time, dust, oil stains or other foreign objects will accumulate, resulting in the bell not ringing.

2. There is oil stain on the surface of the bell: the vegetable delivery bell is exposed to the oil fume and dirt in the kitchen for a long time, which leads to the accumulation of oil stain on the surface of the bell and affects its normal work.