I've filed a claim for a lost MO before (happily 
my PO here is very helpful). Unfortunately, all 
the Japanese dealers I've dealt with ONLY take 
IPMO's, something to do with being easier to cash? 
-_-'

Anyway-
Assuming you kept the MO receipt, there's a number 
you can call to see if it's been cashed yet, and 
then you have to fill out a form sent to someplace 
in Illinois or something. After a while they'll 
mail you back with either a letter telling you to 
wait or with a refund. Erm, I'm not sure how it 
would work with the odd date, but you can always 
try.

Ehh... I can't seem to find the info on the USPS 
site off-hand. You can try the direct approach and 
just tell them that you want to file a claim for a 
lost MO. .. If that doesn't work, I can try to 
find the information again .