I was winterizing my 1987 Bayliner OMC. On the left side of the lower unit there is a plug which is above the top oil plug, when I removed this plug, water had drainrd out, and I noticed that the threaded part that was on the inside of the housing had fallen down inside, so when I went to replace the plug there was nothing to screw it into.Can anyone tell me what this plug is for and how can I get the threaded piece out and reinstall the plug.