First to find out if your mount has declination backlash, just lock the declination knob and then try to move the telescope slight back and forth. If you examine any kind of motion, then you have a declination backlash and depend of its amount can cause some problem, mainly if you plan to use your telescope for astrophotography.
The cause of the declination backlash in HEQ5 has a simple and easy to fixe it source and can be adjusted until to eliminate the problem.
The cause of the declination backlash is the gap between the declination worm gear and the Gear-Wheel.
The larger the gap the biggest the backlash, so it is obvious you have to minimize the gap.
The good news is that the manufacturer has foreseen the problem and the way to correct it is a fair simple process.
First you have to loosen the 3 big alien screw marked with the red arrows on the image 1 below, do not remove them just loose it by 1 turn.
After that you have to adjust the alien screws marked with the black arrows in image 1 and 2.
You have to loosen the (black) screw in image 1 and to tighten the screw in image 2. After about each 1/2 turn, tighten the 3 big screws, lock the declination knob and examine the backlash.
You have to repeat the process, until to eliminate any backlash but also you have to be careful and to give to the worm gear and the Gear-Wheel, a very small gap to breathe, otherwise your Gears will rapidly wearied down by the use.