Windows are Milestone single hung series 1000. Window just falls shut, I am assuming because the channel balances are broken/old. Please advise. The balances I removed are 29 inches, measured as instructed in your video. I have attached pictures of the top and bottom plastic pieces. The balances have a large spring, two small pulleys and a string, I am unsure how they were oriented. Only markings are an imprint of 28E. What replacement channel balances do I order? Thanks.