Both sliding doors (manual) are having issues

Both sliding doors (manual) are having issues. Passenger side has been sliding roughly for some time, so we have stopped using it. It opens and closes, but feels like a roller of some sort may be worn out. We have to push at each end of the door to get it closed completely. The driver side sliding door has started having a similar issue. Also, the lock on the driver side sliding door will not lock or unlock with the key fob or the button inside the van. It can be locked manually, though. Any ideas on either of these two? Thanks!