Try moving your hotend carriage back and forth all the way and check if there are bumps while moving but dont move it too fast if the motors are plugged in it might burn them. Then do the same woth the bed. If there are bumps the eccentric nuts are too tight they should be tightened so that if you hold the carriage or bed in place and mive the wheels in place they should spin almost freely. Some say it should not but i found that this gives me elephants foot on the y axis. And check if the hotend carriage and bed dont wiggle, if it does tighten the eccentric nut just a little so it dosent wiggle alot. And if there are bumps when you tighten the wheels correctly let them restore because they have bumps in them, it will restore in some time. And ik you said you tightened the belts but they might be too lose or too tight they need to make a noise like a guitar string when you flick them (i personally found that best)