Good pick up on the ' Glittery ' draw tube , it really cant help when its sticking in the light path
bit silly really but hey ,,,, it looks pretty
,,, .
I am sure what you did will be more of a help as every little bit helps .
Keep up the good work .
And yes Alex's suggestion really works , I have a Celestron one on my C9.25 and there is a marked difference in contrast between using it and not , especially when there are a few lights about .
Brian.