challenging seller: job description + partnership agreement

In one deal, we're experiencing an owner that we need for his specialty background and tribal knowledge of a niche process.

He's best suited for operations and production on the factory floor, but as the previous owner/founder he fancies himself as the face of all things sales and customer-facing activities.

This takes away from the lead sales and biz dev person while leaving chaos behind on the production floor. Inventory is always wrong, there is zero process, and the team always runs out of supplies to keep manufacturing as a result.

Not to mention there are countless QC issues.

Anyone have experience with this and any guidance on drafting paperwork to keep him focused on production and on task?