When I bought my house in 1999 it needed new windows, so I put new replacement windows in. I went with Simonton Reflections. I called the guy who installed them to see if he had replacement seals for the lower sash. He showed up replaced all the seals and call Simonton because some of the sashes leaked the gas. I never noticed.
He said you bought the best and have a lifetime warranty 100% for 20 years and prorated after 20 years. I have all new window sashes upper and lower showing up Friday.
So if anybody is in the market here is the company.