Have you been able to obtain documents such as naturalization, passenger manifests, vital records, etc.?
These documents may list town of birth for the original immigrants.
Once you have a town name then you can begin searching further back in time.
Have you tried doing a soundex search on the surname on various JewishGen databases? https://www.jewishgen.org/databases/
is a free site and good starting point for census, manifests, naturalization and other records.
Hope this helps,