Just flush it out very very good, you should know about when to stop, basically the point is you want to get the scrap out of down there so that you don't hurt anything when it goes back together, its not something i would skimp on but you don't have to do it for ever either. Basically its just like washing out anything. Just keep doing it untill you feel satisfied that there is nothing else down there that shouldn't be there. I would also keep turning the crank over after to make sure everything feels right if you think there is something wrong just split the case better safe than sorry when it comes to something like this, also when your all done let it dry out good before reassembling the top end.