It sounds like you have developed “ringing”, which look like “echoes” of sharp features or corners because the printhead is moving fast enough to vibrate/resonate itself. Did you happen to lose/damage any of the black plastic collars that are used in mounting the two spacers holding the isolator? If not, you might have actually OVER-tightened those screws. The idea is to reduce the transmission of shock to the printhead cause by abrupt movements (without the printhead becoming loose and sloppy of course!).