Another issue I have heard of is a spark jumping from the Hall sensor directly to the engine frame. Make sure the Hall sensor is sufficiently separated from the engine frame (1/2"+) or well insulated from the engine frame. This includes it's legs and wires running to the TIM6.
Problem: LED does not light.
Solution: The LED should light each time the magnet passes under the Hall sensor. The Hall sensor should be no farther than 1/32" from the magnet when the magnet is directly under. Also, the polarity of the magnet is critical. The south pole of the magnet should be facing the Hall sensor. If the distance and polarity is correct, you may need to replace the Hall sensor. Temporarily bypass the Hall sensor by shorting pins 2 and 3 of the Hall sensor. If the LED lights, then the Hall is bad.
Problem: LED lights, but does not blink or turn off when the engine is cranked.
Solution: Disconnect power immediately! Your TIM6 is not working properly, is probably overheating itself AND your coil. The LED should light ONLY when the Hall is in close proximity with the magnet. Most likely a bad transistor or Hall. Replace the following components one at a time until it is working as expected: Hall, then the small transistor, then the large transistor.
Problem: LED blinks, but no spark.
Solution: Disconnect the coil. Connect a voltmeter to the coil connections on the board. Position the magnet so the Hall sensor is activated, and the LED stays on. Quickly note the output voltage then disconnect power to keep from overheating your TIM6. The output voltage from the board should be roughly 3/4 of the battery voltage, i.e. if you are using a 6 volt battery, then output should be 4.5 to 4.75 volts. If you are not getting any readings, then one or both of the transistors on the board are probably bad. E-mail me if you want replacements. These run roughly $6 for both, including shipping. If you are getting a good reading, then test the coil by checking the resistance of the primary and secondary windings. The resistance should match the coil specifications. If you bought a coil from us, the specs are on our web page.
If everything seems to be working except you get no spark at the plug, I suggest removing ALL the components from the engine, including the spark plug, and reconnecting it on your work bench. Make sure you run a wire from the plug threads back to the coil negative (or TIM6 ground or battery negative). If you get it working on the bench, then reinstall one component at a time on the engine and re-test until you find the fault.