Chainsaw Repair

I have a CS660EVL with 24" bar. It starts and runs OK but after say 20 minutes use it suddenly dies just as if I had hit the kill switch. If I remove the spark plug and spin the motor, there is no spark. When it cools down it will start and run again for a while, as though nothing had happened. I am assuming its an ignition module failure which is bad news as the module seems to be an obselete part. Any thoughts, and specifically, does anyone know if a different module can be made to fit. It's way too good a saw to throw away! Thanks.