---

It sounds like you may have found the problem, but I am not aware of the brand you mention. The very low price generally indicates it is a foreign knock-off part, so be careful. I generally try to find current or left over Mercury/Quicksilver parts when possible (many parts are already discontinued). I have also found CDI Electronics or Sierra to be reliable aftermarket ignition system parts, generally 30 to 50% less than Mercury.

For the cost saving you might give the aftermarket part a try. Since this is not a component likely to result in engine failure on the water, (as long as you keep an eye on engine temp and oil supply) it's not that critical. If it fails quickly, and the horn starts going off at odd times, you can always upgrade to the Mercury part.