Additions of (4) roller pick-ups to a lot of newer issue 3 rail engines was a big plus, Atlas also has added small capacitors to smooth-out, bridge over, some of the intermittent operation of AC roller pick-up power. Cleaning/lubricating pick-up rollers a big plus. Wheels and flanges can also acquire a lot of dirt that tends to inhibit electrical flow. Basic maintenance. IMO, Mike CT