Who bought the windows?

If the contractor did, he is responsible for fixing mistakes or making the manuf. fix them.

If you bought the windows, the contractor deserves his money, as the mistake something with which he had no control.

Contractor bought the windows. So should I hold back full window payment or some percentage? There are probably 7 or 8 with the problem.

Something fishy here.
Who measured and ordered the windows?
Who discovered the discrepancy and why did the installation continue?

My contractor hired a window company to measure, order and install. The windows in question are all same sized sliders in my basement. All the frames look good and fit the openings well.

I noticed the problem after they all were installed. I was making my rounds checking each window and noticed the locking was pretty touchy if they weren't lined up exactly. I found out when I locked them the sashes move in the frame a good half inch left to right creating a big air leak if they aren't centered in the frame. I found one of these same size windows which is correct so it appears some were built wrong. I figured they would be set up on some sort of jig so I'm surprised this happened.

Thanks for the follow ups so far.

Perhaps figure out the window cost for those six and hold back that amount? You need to hold back enough that they don't forget about you.

I'm not a window guy, but for that half inch, I'd almost be inclined to have them install a filler strip in the channel on each side and get a discount.

"My contractor hired a window company to measure, order and install."

So, the contractor DID NOT purchase the windows, the subcontractor did.

The contractor will refer this to the sub, who then referes it to the mfg.

Withold the payment until the matter is resolved to all parties satisfaction.

Window guy is coming out this week. Thanks for the advice everyone