The four,
S377-19 (1820) balances of my order do not fit my window sash. They do not engage into the sash and simply come out. My existing balances are 18 1/2" long (metal section only), but the ones I received are 19". I checked the website again and the 18" series only have the four-digit number of 1720 and not a 1820. What is the solution to this? Let me know. All the other balances I rec'd went in perfectly. Thank you