We were recently traveling back from a ski trip and making the descent from the lodge at 8,000 ft. The roads were sporadic, ranging from severe snow and ice to some parts of the road being cleared by plow. My buddy kept wanting to put on and take off the chains every couple of miles. He said he had a mechanic tell him the chains would ruin the tires very quickly. Five minutes later we would run into another stretch of road that had severe conditions. In the scenario described do the tires get affected that easily for a need to take the chains on and off every couple of miles or is it best to leave the snow chains on until getting down the mountain? I am an advocate of keeping them on until you get below the snow line. I could buy the argument if we were riding for 500 miles with chains going 50 MPH, but we were going 20 to thirty in severe wintry conditions through mountain passes. This was the Alps to put it in perspective when I describe the snow as severe. 4 ft. + of snow on the ground and snowing.
Just buy a new one, it is cheaper in the long run.
Basically, what happens is in the sensor that is on the window there is a magnet. when the two sensors are next to each other, the magnet closes the switch and the circuit is complete, when the sensor is not there, like when the window is open, the circuit is broken and the alarm goes off. So what you do is you cut the two wires connected to the top sensor, strip the wires, and close the circuit, and the alarm wont go off when you open the window. it will not harm the rest of the system at all.
You could call your local fire department to get some names of people who are in the business of servicing fire extinguishers to get an idea of cost. You might find it's cheaper to simply purchase a new comparable one than having your existing extinguisher serviced.
