Caldwell & Unique Channel Balances

Recently purchased patio home, three months ago. Over the past weekend attempted to open one of the windows, was stuck and broke the channel balance. It came loose, believe I broke the take out clip. Noticed that the springs are rusted together, believe the channel balances should be replaced. I have the old channel balance and havev measured. They are 29" long, 9/16" wide. It appears that they are Series 351, with 19-002 top attached and 15-002 shoe attached. Not absolutely sure about this part as the Series 390 looks much the same. Guess that I should have new take out clips as well. The channel balances that I am replacing one says "28 1/4 3 CALDWELL GM" the other says "UNIQUE 28-B-20". Any advice?