Replacing a kitchen faucet when the mounting hardware is seized can be a challenging task, but with the right approach and tools, it's definitely manageable. In my experience as a service plumbing technician, the first step is to ensure safety by turning off the water supply and clearing out the area under the sink for easy access. When the existing faucet's mounting hardware is corroded or rusted and won’t budge, trying to force it can cause damage to the sink or pipes. In such cases, cutting out the old faucet, although more drastic, is often the safest and most efficient method. Specialized tools like a reciprocating saw or an oscillating multi-tool work well for this job. After removing the old faucet, carefully clean the mounting surface to remove any debris or old sealant. This is vital to ensure a tight seal with the new faucet and avoid future leaks. When installing the new faucet, use plumber’s tape on threads and apply appropriate sealant if recommended by the manufacturer. Once installed, test the faucet thoroughly by turning on the water supply and checking for leaks. Don’t just test the cold and hot water flow but also inspect under the sink where the connections are. Ensuring no leaks and smooth operation will save you from costly repairs later. Through performing faucet replacements frequently, I’ve found that patience and preparation are key. Sometimes, replacing seized hardware requires extra care and improvisation. But ultimately, a fully functional kitchen faucet that operates without leaks is well worth the effort and brings great satisfaction to homeowners.