Hoping to find replacement for my 25 7 Milgard balancer

It's hard to tell what you have just based on the stamp. All that tells us is how strong the spring is. That said, Many Milgard windows have been known to use our Series 385 channel balance. For you, I'd start with our S385-26 and see if that's a match. It comes with the 19-005 top and 15-004 bottom which you will need to look at to confirm if it's a match.