American Jawa sold these as Zetors, however they were... I think Agrostroj prostejov made.
The former state company is continued in Wisconsin private company, http://www.wisconsineng.cz/CZ/index.php?option=com_content&view=article&id=27/
I dont know any representatives, but i'm sure someone in Central Europe has parts for a TZ-4-K14 which the original company dubbed them.