As has been noted, Lithuanian does not use the letter "w" so the surname would begin not with "w" but with "v". Lithuanian also does not use the letter "x" but "ks" instead, so Alexander is Aleksandras in Lithuanian. If you look at a city directory for DuBois you might find alternative spellings. I cannot find any listing in the online phone book for Lithuania for any surname beginning "Valint-" with a "k" in it.
You might try obtaining his church marriage record which was probably made by a Lithuanian priest and might therefore have a more definitive lead on the surname as well as his birth place.