I was able to buy exact replacements in 2003, but can't find them now. The channel is 19-1/16 inches long. The photos show the relevant parts and markings. Window Master was purchased by Jeld-Wen sometime prior to 2003. They say these are Caldwell balances and the replacement is the Jeld-Wen 18-4. To me, that doesn't sound right as the channel in 19" long not 18".
Can you help me? I am looking to buy 6 sets to fully replace all balances and have 2 spare sets left over. (Hopefully to last another 28 years!)
Joe
