python 902 alarm problem

I have a 2000 Mustang GT that I bought a couple years ago with a Python security system already installed. I believe it's the model 902 system with a 2-way key fob. Last year, the alarm stopped working. When I walked out of the gym one night, I had to press the button on the key fob for a few minutes to get it to finally disarm. It gave me a strange number of chirps (similar to if the alarm were set off while I was away). I was able to use the alarm one more time after that, and if I recall correctly, I had a hard time both arming and disarming the alarm, as if the system wasn't communicating with the fob correctly anymore. I believe the key fob also beeped a code once or twice. Now, it won't work at all. I hit the lock button and a couple seconds later I get the "you're too far away" beeping from the fob, despite being right next to the car. I've tried all the obvious things I can think of (replacing the fob battery, disconnecting power to the car for a while, etc) and nothing works. I'm guessing it's shot and needs to be replaced, but I'd like the opinion of someone who knows more than I do. For all I know, it could be something stupid like a loose antenna wire. If it does end up needing to be replaced, can I just buy a new one and swap it out, or is there more to it than that?

Try disconnecting the antenna (the one on the windshield) for a few seconds then reconnecting it. This should re-sync your remote...it will not address the other issues you mentioned, but it's a good place to start.Installer, IT support, and FFL. I need less hobbies.