Here are some ideas:
http://forums.radiocontrolzone.com/s...ad.php?t=17781
http://www.gl1800riders.com/forums/v...eca00bae5bb4d3
http://forums.radiocontrolzone.com/s...d.php?t=150752
http://www.girr.org/girr/tips/tips7/repair_tips.html

To some it up: recomendations seem to be fill in the whole (or partially fill it in) with CA, or hot glue, or plastic resin ect.