Were these drawings ever synced back to the master after being uploaded to the replica site? If the replica site is seeing communication issues, then they may still be just on the replica site. When you try downloading the drawings do you see any errors in the MS logs on the replica sites? If not, then it might be a network level communication issue.
In terms of recovering the drawing data, if you're just looking to get the physical file for the drawing, then that's definitly possible. You can get the file name and path by either querying the DB, or by using the -checkBusinessObject flag on the WContentVerify utility. Then, you can just access the file from the filesystem.