Keep it unused until the manufacturer's requirements are confirmed and the correct accessory is fitted. A baffle may control splashing, material ejection and operating noise; it is not simply decorative rubber.
What the observation tells you
Do not cut away torn sections, substitute a generic sink mat or run the appliance to compare noise without it. The relevant part must match the actual model, including whether it is owner-removable. A missing piece also raises the question of where that piece went.
A useful next step
Retain damaged parts and photographs for identification. Tell the engineer if a fragment may have entered the chamber so it can be assessed before restarting.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.