Re: Cobra upper unit coolant drain plug
welcome to the club! I did this a few weeks ago, but I managed to get it back on without taking the drive off. There is a rectangular metal piece that has a threaded hole in it that the screw threads into. It is bigger than the hole and holds the the plastic insert in using the screw. In my case the metal piece didn't fall far. I ground down a cheap plastic dental mirror so it could fit in the hole so I could see where it went. I had the drive in the up position so it fell toward the bow. I dropped the drive down so it would be easier to get out. Once I found it I used a piece of wire, bent the tip 90 deg, and fished it out using the mirror so I could see what I was doing. Once I got it out I got some fishing line, looped it through the plastic insert and around the metal piece. keeping the line around the metal piece I carefully put it back inside the drive and pulled on the line so it would stay in position. Then I put the plastic insert back into place while still keeping tension on the line. Next I spread the 2 pieces of the line out so I could put the screw into the plastic insert. then I carefully turned the screw until it caught the threads in the metal piece. once I knew it caught I pulled the line completely out and tightend the screw. I did this by myself but I think it would be easier with 2 people, one to spread the line out and one to put the screw in.
I hope this helps.