Not sure if this will help, but worth a try:
I posted on my blog a while back how I fixed my brother-in-laws cordless phone. Go to:
http://www.electricalrepairlinks.com
and navigate to the "My repair projects" blog on the top menu. Category is "MD400 Cordless Phone".
Regards,
Tim
http://www.electricalrepairlinks.com
Tim, July 2006