Joe Hudacek has been doing this for decades and has a good reputation in the antique Cadillac community.
Joe Hudacek Rebuilder of Ranco and RobertShaw heater valves. New Ranco heater valves for sale
6606 Banks Avenue
Superior, Wisconsin 54880
715-392-6169
Cell: 218-213-8906
http://www.heatervalves.net/I believe Atwater Kent rebuilds these as well.
Temp sending units, coils, fuel sending units, tube radios, vacuum advance, voltage regs 1920s to 1970s (mostly 30s, 40s, 50s)
Atwater Kent
12 Jacques Street Worcester,
MA, 01603
(508)792-9500
http://www.mykmlifestyle.com