bed bouncing during print

manually moving bed, also notice the acme rod that the bed rides on, doesnt seem to be an issue even though its not mounted on the lower part of the case.  i thought that perhaps that was causing a deflection/vibration while printing, but that doesnt seem to be the case.

the metal frame that holds the heated bed is attached to the plastic carriage that rides up and down the rods for the z axis by one phillips screw on either side.  i suspected these to be loose so i tore the printer apart to get at them to tighten them.  im not going to say that they were loose, but they certainly werent tight either.  im going to do some more poking around tomorrow and maybe figure out how to better attach that metal from to the plastic carriage.