Well I am glad it didn't cost you anything, cheapest repair I ever did, LOL. Hey, at least you found out they don't work now when you can fix them "before" you have a problem and do need them to work. We had a discussion about this safety device on another thread. I would become familiar with the process and be aware of what can happen to your blower seals if you pull the trap door when the motor is running at rpm above idle. If you don't have a CO2 fire extinguisher, I would recommend one be kept near or in the ER, it will choke off the air going to the engine. I pulled stops once on an engine on a friends boat, but it was still running, albeit at a much lower rpm, it took shooting the air intakes with an extinguisher to finally shut it down completely. I used what was handy at the time which was a Halon type, but CO2 is the preferred extinguisher for this situation. If you ever need the emergency stop you will be glad they are there! If you want to know what a Detroit sounds like that is over revving go to a tractor pull and stand next to the track. Now imagine being in the engine room with the same beast trying to blow itself up! NOT FUN, I had to throw out a perfectly good pair of underwear after that adventure. If it happens you don't have much time to react before something catastrophic occurs. I just happend to be in the galley when that one started to run away and was close to the ER, the engine didn't grenade, but most will if prompt action is not taken.