Did EnDuraLast Ignition System just Die? BMW Airhead Misfiring, Sputtering, Stalling

After complete restoration of our 1977 BMW R75/7, this is the first problem we are experiencing. Bike's ignition misbehaves when outside temperature reaches 30C. Misfiring can be so bad that it is impossible to ride it. When cools down or when outside temperature drops, bike runs fine again. Troubleshooting says it is electronic ignition system we have on the bike. DISCLAIMER: In no case I can be held liable for injury or damage resulting from alterations or work you make to your motorcycle. Please seek for qualified assistance before doing any of the procedures outlined here. If you still decide to proceed, you do so at your own risk.