polarscope reticle alignment - how close?

[michaelmorris]

I've just bought a 2nd hand AZ EQ6 GT mount.  One of shakedown items is to check the alignment of the polarscope.  It seems very well aligned.  When I set it on a distant tree branch and then rotate the RA axis though 180 degrees, the error is about the same as width between two of the three tracks of the central alignment circle (It's the new style polarscope reticle).

I know from past experience with polarscope reticle alignment on my HEQ5Pro that even a very small movement of one of the grub screws can result in a large deflection of the reticle. 

I will be using the mountn for visual observing and guided DSO imaging, subs of up to 15-20 minutes for narrow band imaging.

Given the small size of the existing reticle alignment error, do you think it is likely to worth the effort of trying to dial out that last bit of error?