Doors and windows not opening or closing as they should, can be a problem, if not fixed properly can lead to other problems.
Planing closing edges can upset clearances or water and wind resistance.
Often hinges get paint or corrosion build up, which shifts the hung member towards the closing edge. Often it is best to replace hinges with proper clearance of 2 mm, which can result in no planing required.  

Double Hungs are difficult to pull apart and assemble. Mostly paint buildup stops them sliding. A scrape and sand of paint from guides and a rub of candle wax, could be enough to get them working.

If in doubt give me a call for a no obligation free inspection.