You post doesn't give us enough information to do more than guess.
It is possible that the previous owner had the windows out to clean, and didn't put them back together properly. Sounds like you took care of this.
Don't know what type of climate you live in? Thermal effeciency is more important in Montana than in Georgia. Try them for a winter and see how they perform. Check for air leaks, condensation, etc. Then make your own decision.
Obviously, these windows are better than the aluminium sliders used in the 60s and 70s.
If you have any more questions, feel free to post. And, remember be VERY specific and provide plenty of information so that the respondents aren't left guessing.