Braun's Series 9 Pro is a premium foil shaver typically used daily or several times per week. Most performance complaints are consumable-related: foils and cutters wear and cause pulling, irritation, or reduced closeness long before the shaver is "dead." Batteries are the next major limiter; reduced runtime and inconsistent charging usually indicate battery aging or a charging-port issue.
Water exposure in wet/dry use can also stress seals and internal boards over time. Repair is generally worth it when replacing the battery, a charging component, or the drive assembly, especially if the body and head mount are intact.
Replacement becomes more rational if the shaver has corrosion from water intrusion, repeated charging failures, or a cracked housing that compromises waterproofing. Budget for regular foil/cutter cassette replacement when deciding whether the device is truly failing.