Thanks LittleToe for your quick reply.
So I assume it must be like "being tested as to fitness first". Can I guess correctly and say that not many elders wish to be a CO?
I know that elders would encourage and give a workload to ministerial servants to see if they are capable enough to qualify eventually for eldership. Of course, a MS who eyes the position of elder would take all tasks and voluntarily do extra in order to attain such a status. I suppose that is what a CO does to various elders too in order to find someone willing. Then a willing elder would try and make his light shine when given the opportunity.
I'm speculating at this point. However, I notice that a certain elder in my congregation is itching for something higher.
Alligator Wisdom (aka Brother NOT Exerting Vigorously by WTS standards)