The Fossify suite (like the gallery app that was linked to in the OP) was forked from this. Simple Mobile had been bought out by an ad company or something last year, so the community moved onto Fossify. Note how Simple Gallery has not been updated in over a year, and was removed from F-Droid.
Make sure your Z axis rods are:
My guess is that something is wrong with one of the rods about four inches up.