I tried resealing my sensor with some sensor safe RTV a while back, waste of time, it dose not leak from around the threads, it leaks right through the unit and out the connector. Just replace the sensor on your next oil change. Replacing it is not so hard, just figuring out how you have to contort your body and arm to get leverage to get it out takes a few tries.
On the subject of squeal, you can troubleshoot belts, pulleys, and devices like alternators, P/S pumps and AC comps by removing belts one by one, starting with the alternator belt, starting the engine and running it for a short time (it will run off the batt, and WITHOUT THE COOLANT PUMP TURNING) to see if the squeal is there or not. I had mine running with no belts at all, it turned out to be my water pump making the noise. With my engine off and no belt on the water pump/fan, I could spin the fan by hand, thus turning the WP and I could hear it squeak. So in my case, all my belts were fine.