RobertG, I strongly recommend you do one mailing with a separate ballot vote on each item (section) proposed to be amended. Also, include a cover letter listing the pros and cons of each amending each item.
The reason to list each change separtely is because it can be difficult to get just one change approved. It can be almost impossible to get 2/3 of all owners to approve when you lump them all together because when an owner does not agree with a single item they will have to vote to oppose the entire group of changes. Often it is difficult to get 2/3 to respond; and no response is equivalent to a no vote since it requires 2/3 approval.
Remember to allow follow up time to knock on doors if necessary
RogerB