The project manager should review the terms and conditions of the contract to determine if the maintenance manual was part of the agreed scope and deliverables. If the manual was not included in the contract, the project manager should inform the customer and negotiate a change request to add the manual as a new deliverable. If the manual was included in the contract, the project manager should apologize to the customer and expedite the delivery of the manual as soon as possible. The project manager should also update the risk log to capture the potential impact of this issue on the customer satisfaction, project schedule, and budget.
References: (Professional in Business Analysis Reference Materials source and documents)
* PMBOKGuide, 6th edition, Section 12.2.1.1, "Procurement Documentation"
* PMBOKGuide, 6th edition, Section 12.3.3.1, "Change Requests"
* PMBOKGuide, 6th edition, Section 11.6.1.1, "Risk Register"