A maintenance window is a predefined period of time during which planned changes or updates can be performed on a system or network with minimal impact on the users or business operations1. A project manager should consider the maintenance window next when deploying a new networking device into an existing production environment, as it will help to reduce the risk of downtime, disruption, or errors. A maintenance window should be scheduled in advance, communicated to the stakeholders, and aligned with the change management plan2.

This answer is based on the best practice of issue management in project management, which is to identify, analyze, prioritize, and resolve issues that affect the project performance, scope, schedule, quality, or budget12. The first step in this process is to rate the severity of the impact the issue has on the project, which involves assessing the likelihood and consequences of the issue, and assigning a rating or score to the issue based on a predefined scale or criteria34. By rating the severity of the impact, the project manager can determine the urgency and importance of the issue, and decide the appropriate course of action to address the issue56. Rating the severity of the impact is better than the other options because:
Buying a replacement for the faulty equipment may not be feasible, cost-effective, or timely, depending on the availability, price, and delivery time of the equipment. It may also require approval from the project sponsor or other stakeholders, and may affect the project budget or scope7.
Getting the maintenance team to resolve the issue may not be possible, depending on the nature and extent of the malfunction, the skills and availability of the maintenance team, and the warranty or service contract of the equipment. It may also take time and resources to diagnose and fix the problem, and may cause further delays or disruptions to the project8.
Escalating the issue to the project sponsor may not be necessary, depending on the severity and complexity of the issue, and the authority and responsibility of the project manager. It may also create unnecessary alarm or confusion among the project stakeholders, and may undermine the project manager's credibility or autonomy9.
Reference = CompTIA Project+ Certification Study Guide, CompTIA Project+ Certification Exam Objectives, What is Issue Management?1, Issue Management Process2, How to Assess the Severity of Project Issues3, How to Prioritize Project Issues4, How to Replace Faulty Equipment in Project Management5, How to Manage Equipment Maintenance in Project Management6, How to Escalate Issues in Project Management7

Explanation
The project manager should communicate with the affected stakeholders first after realizing that the sign-off for the project scope baseline is delayed due to multiple changes and that the budget for this project is restricted by the project sponsor. The affected stakeholders are those who have an interest or influence on the project and may be impacted by any changes or delays. Communicating with them can help to explain the situation, assess the impact, seek feedback, and manage expectations.

Meeting minutes should be prepared to ensure team members who are absent remain informed about assignments. Meeting minutes document what was discussed, decisions made, and assignments given during a meeting, providing a record of the team's progress and ensuring absent members are up-to-date. References: CompTIA Project+ Study Guide Section 4.2.2 The project manager should prepare meeting minutes to ensure team members who are absent remain informed about assignments. Meeting minutes are a written record of what was discussed and decided in a meeting. They usually include information such as attendees, agenda items, action items, decisions made, issues raised, and deadlines assigned. Meeting minutes can help to communicate important information to team members who could not attend the meeting and provide a reference for future follow-up.

Explanation
RACI is a tool that best illustrates how team members with different roles should interact on the team. RACI is an acronym that stands for responsible, accountable, consulted, and informed. RACI is a type of responsibility assignment matrix (RAM) that defines and clarifies the roles and responsibilities of each team member for each task or activity in a project. RACI can help to improve communication, collaboration, and accountability among team members and avoid confusion, duplication, or conflicts3