Dear friend!
If the WSMD4 board needs to be replaced within a short period of time, please make a strict cutover plan in advance (check whether services are allowed to be interrupted). You are advised to configure optical cross-connections on the new WSMD9 board before service cutover based on service requirements,and set the proper Optical Interface Attenuation Ratio on the WSMD9 board. If it not set, the optical services will be blocked.
Good luck!