If he is the original owner of the windows, he should contact the original manufacturer and see if they will honor the warranty.. Many window companies warranty the glass seals for between 5 and as many as 20 years, but only to the original purchaser of the glass. If you bought the home new, you would qualify. If you replaced the windows in your home, you would qualify. If you bought the home used, and the windows were already there, you MIGHT qualify. The point is, DON'T do anything until you find out if you DO Qualify, or you could void the warranty and cost yourself $$$!
Other than that, I have never seen a unit like this repaired, they only get replaced. Most glass shops throw the unit away after they replace it.