Thanks for the replies. I've continued my research since my post, including looking back at earlier forum posts (which I should have done first--my bad!).
We are located in North Florida. I had read good things about Suncoast Designers near Hudson, Fl, which is only about 3 hours from us. They offer a lifetime warranty on window repairs, and have on-site RV facilities (power, water, dump station). I contacted them (very pleasant to work with) and have an appointment late this month.