If you get a 10000101, 10000100, 10001100, 10001101 Error then you need to reseat or apply pressure to the E3's clip and try again.

When you initially clip onto a fresh board it will 100% make a clicking sound when it is fully attached. This does not guarantee it will work, but its a good indicator. Generally you should get the E3 clip and put it on an angle (45 degrees) next to the NOR (so you can see the clip's pins), align that with the pins on the NOR chip and drop it down like a lid.

Regarding pressure, it all depends on how many times you have tried to clip it. The more you clip onto the NOR the weaker its pins get, it will no longer make that click sound and it won't stay on its own. If you are after a permanent install you should put some foam or something squeezable on top of the NOR chip (roughly 2-3cm tall that can compress to 1-1.5cm) and reassemble the PS3 (Which causes pressure on the NOR). If you do not care for a permanent install try using a clamp, clip or vice as seen in this image.

Once you have got a successful read you shouldn't start assuming its error free. Check the dump you have and if it appears valid you should not be touching your clip again (to prevent any bricking when downgrading).

Checking the NOR backup for errors