having the cheshire is not enough to get proper collimation, there are 4 different things to correct and for proper collimation you require 2 to be correct.
A plain laser does only 1 of 4 of which the cheshire corrects the same error.
Barlow laser and laser correct two of the four but it just doesn't do it that accurately.
Auto collimator (original type with a central peep hole will do 1 of the 4)
Auto collimator (improved with an offset peep hole as well as a central will do 3 out of the 4)
The sight tube is also important and if you know what your looking for in the actual image you can see if you have it right or not.
Upgrade the springs on the mirror cell, if the mirror cell only has rubber O rings, get springs to fit in that are solid makes a huge difference
Your secondary vanes have to be tight. mine have just started to cause a slight divot into the OTA thats how tight they are. Though i have also upgraded the whole front secondary you can see that
here the vanes are 1.7 odd mm instead of 0.7mm I did this for two reasons, visual, i like diffraction spikes it makes the stars interesting. and Strength when collimating.
The 0.7 vanes are more than capable of holding the secondary without flexing about as long as you tension them up but in the rotational direction they will flex like a bugger making collimation quite hard.