Bell ringing can lead to long term illness and muscle strain. Due to the motion involved there can be a risk of repetitive strain injury and other associated problems from manual handling.
You should consider risk assessing the activity and understand the risks posed. Inform those involved of safe methods of work and assess whether those persons involved are suitable to undertake the task is good practice.
It may be safer to leave bells in the “down” position when the bells are not being rung, your risk assessment is likely to assist you in understanding safe working practises for your equipment.