A friend brought me his aluminum frame/steel slide 1911 so I could look at the problem he was having with it. When shot or cycled by hand the slide sticks at it's farthest rearward travel and will not return forward without bumping it toward the front. I disassembled it completely and thoroughly cleaned and oiled it, same result. Any tips on where I should look for the cause of the problem? Your hints and advice would be more than welcomed.