Ladder problems
From GcatWiki
It seems as though everything equal to or greater than 500 bp is off. The first images are taken from a 0.4% gel. As you can see, anything equal to or greater than 2000 bp is off (the very first picture is the raw data, the second is marked up). The second image is taken from a 1.6% gel. As you can see, anything equal to or greater than 500 bp is off. The new MWM's bands are less heavy making any bands measured by this marker appear larger than they are.