the pins don't wear down, but the springs. as you have to move the coil around, it could also be a break in the cable itself, usually the plus cable. try a different charger, check for differences. post.
Check under system whether USB port is still available, recognized and used. Post results. Having used any other item that draws power from the USB port, add that item and see whether there is still current flow ( for example an iPhone, an iPod, a rechargeable battery.) post results.
If you haven't solved the issue yet, and the D.C. N Board is not at fault, run aht and post the results - Update (06/06/2018): aht will give you a mistake in the area of the current check, usually a 0 Ohm resistor in the R70xx area of the power supply area.