Customary legal services fees range from $250-$500 per hour, dependent upon locale. A competent business lawyer would likely charge between $750-$1,500 to revise an LLC operating agreement -- the difference in cost would largely depend on how much revision and fact gathering is required before drafting the modifications.
However, the bigger difficulty in this scenario may be obtaining the consent of the allegedly unproductive partner. Because, if that person refuses to consent to the amendment of the operating agreement, then the other two partners may be required to ask the court to dissolve the LLC, because that may be the only means of removing the unproductive partner from the business.
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