When I press the lock/unlock switch on either front door, I can hear loud motors spinning in both doors, but nothing happens (my doors don’t lock/unlock). My last 2nd gen I owned had the same problem, but I never bothered to fix it. I really want my doors to lock without having to manually lock them with my key.
1999 Dodge Ram 2500 5.9 Cummins sport. 

Go out to Harbor Freight and get the door panel tools. Now go out to Amazon and order a bag of door fasteners (plastic clips). When you are using Harbor freight tool to slide it along the bottom of the door till you hit a plastic clip saddle it in the middle and pry it out. Once the door panel is off you can work with both lock motors in cleaning and lubing them. If that doesn't help then replacement might be required. As for the bag of clips you'll need them to re-install the door panel you manage to tear up every single clip but aleast you don't damage the the door panel.

thanks for the idea on new fasteners just tore the door panel off for passenger side bad window switch. took the switch apart and it is mechanically bad switch for the window portion of the switch. ordered an original mopar switch maybe work for the next 20+ years.