The best 9004 sockets I have found come from Innova Design:
www.headlightplugs.com the quality of the ceramic and the connectors are
both significantly better than anything being shipped in from overseas.  By
definition, all 9004 plugs have to be the same.  The problem is most likely
either a massive lack of quality control or an incorrectly labeled package
from Calterm, who tend to be on the low quality side of cheap aftermarket
parts.

Jay Brown
'85 Zetec Westfalia
https://sites.google.com/site/vanagonheadlightrelays/