Without knowing anything about how the DWGs were created in the first place, nobody can tell you much. There is no "one fits all" DWG. Each CAD program may embed different data and use a different sub-version of the format. You have to educate your clients about that and request the fi8les in a format can handle. Failing that, you might consider getting a tool like the free DraftSight to check and convert the files, but even there not all files may open.
Mylenium