I've got a '50s kitchen cabinet with sliding glass doors. These are becoming increasingly difficult to open and shut. I've tried some strategic sanding and put a bit of furniture wax in the runners to no avail. Any suggestions?
Take the glass out by lifting up and tilting the bottom out. Carefully smooth the bottom edge with fine emery paper. The glass will have dug into the wooden groove over the years, making it rough. Smooth the groove with a fine flat file and melt in a little candle wax.