+1 to roof35's comments. Sounds like a botched install. Plumb and level are of little consequence (within reason of course), the main concern is that its square. Your installer should have put his level away and adjusted the window based on the sash to frame reveals which would have alleviated this. Regarding the hardware, Marvin uses the same (or similar) hardware as any other window company. I can see why you might think that is looks insufficient, however it is all engineered with maximum capacities based on size, weight, etc. Reputable manufacturers like Marvin are very conservative in staying well within those parameters for long term performance. It sounds like you are now stuck in the unfortunate situation where you sourced the windows and hired a guy to install them. This situation results in failure at a very high rate and inevitably ends in finger pointing. Your best bet at this point is to get the installer and a manufacturer or supplier rep there at the same time to hash things out and come up with a gameplan to address.

Check out sash curtain rods which mount almost flat on the surface. They come in traditional flat shape or small diameter rods. I like the film or you can use the window spray on frosting although you will need a steady hand or it won't be even coverage. If you do the spray, you can use make a pattern on the glass with narrow masking tape which leaves you a nice even area to look through but from the outside it is still difficult to see through unless you are right against the glass like a peeping tom.

I am not someone who posts reviews on the internet, particularly negative feedback. But, given how much false information and untrue ads are out there for the “high quality” of Marvin, I have decided to do what is right and post my experience with them on a few websites, such as Houzz. Four months after we placed the order, Marvin delivered the windows. Some of the windows had obviously been dropped before delivery. Scratches on the outer frames and bumps on the inner side clearly showed that. We noted the issues as they were unloading the windows and took pictures on their truck. They may claim that they have good quality windows, but when they are dropped it basically does not matter anymore as the structure of the windows is certainly compromised. As for customer service, the windows were delivered in April and we notified the vendor and Marvin of the issues immediately as they were still unloading the windows. Four months later, we are still nowhere and nothing has been fixed. They just delivered one wrong frame for a window which we never asked for a fix and they are not even coming to remove it from my property. No word on when they are going to fix the windows. Total mess on their side and non-existing post-sale support. === Update of October 2021 I got an email from Marvin regional manager today; and it's the middle of OCTOBER -- 6 months after installation date. They plan to replace the broken sashes -- get ready -- in JANUARY NEXT YEAR. This joke is not even funny. Stay away from this company at all cost. They couldn't care less about you once they have your money. Go with anyone but Marvin. I mean, the worst thing that can happen is that you get broken windows and they never fix it --- well, that's Marvin.

Thanks for you reply. They are 3 feet wide. I agree they might be hard to operate and also worry about hardware over time just because it's got to be such a heavy window. Marvin makes them.