I have the same problem with my newly purchased 2001 Monte SS. The passenger seat works perfectly however the driver seat is completely inoperative. I have plans to investigate and hopefully fix it this weekend. Following the detailed directions in the above post is the best way. Simply using deductive reasoning is always wise.
With regard to the availability of replacement elements all hope is not lost. Dorman is a major supplier of aftermarket and OEM parts. This link will take you to their site where several heater elements are listed. PLEASE Finish reading this post before you go there.
Dorman Products - Seat Heating Pads
Part numbers 641-101 thru 641-107 are all GM replacements. The kits listed also come with the hog ring pliers and new hog rings. (sweet) Be aware that there is not an application listing a replacement for the Monte Carlo, HOWEVER there are listings for suburban, yukon and tahoe. They may not be an exact fit but if you want a new element rather than trying to repair your old one then this is certainly the most viable option. The other plus is that in keeping with GM technology I have to believe that the elements for the suburban, yukon and tahoe will have the same electrical requirements as a Monte Carlo thus matching the circuitry. There is always a possibility of problems using an aftermarket "universal" heater element with your cars' original wiring.
The other option is simply using the passenger side element. YES this is the more labor intensive option BUT it is the cheaper one. The only thing you must remember is to be very careful when removing BOTH the driver and passenger side. After repairing the driver side element just swap it with the passenger side. Since most people only use the driver side you will be much more likely to not have to repair either of them any time soon.
I will take photos and update this thread after I repair mine this weekend. I also have several breaks in the rear defroster glass that I am hopeful to repair. If I am successful then I will post this on a different thread.