You can get Hasegawa replacement parts through Hobby Link Japan. Their replacement parts FAQ is
http://www.hlj.com/faq/q41.html. Just follow the instructions.
There can be a considerable waiting time, but don't worry too much about the cost of parts and shipping. They are honest and reasonable. They didn't even charge me for the last sprue sheet they sent me. Of course, I ordered the original model from them, so they may have taken that into account.
Ddms