Wood windows can be dry-rotted, glazing putty checked or missing, in need of painting, painted shut, ropes broken, etc.  The extent of the repair needs to be weighed against the benefits of new windows, versus repairing them.

Aluminum Window defects usually have to do with their operation.  They may not slide properly, the locks may be defective, or the window may have warped and won't close without a fight.  In many cases the parts to the older aluminum windows aren't readily available, or the repair job is a stop gap measure.

Steel window defects manifest themselves in two areas: Steel rusts and is impossible to keep rust free, or the locks and hinges are frozen or painted shut.

Every consumer must weigh the cost of new windows against repairing the old windows.  Many times the cost and benefits of new windows outweigh the costs and trouble of maintaining windows that are at the end of their life.