[Nexstar 127]Is my DIY collimation cap(and collimation on my scope) good?

[IWatchStars]

Hi,

I own a Celestron Nexstar 127 SLT and I tried making a collimation cap for it from a metal container cap i had lying around. This is how it turned out:

- You can see the black spots because the metal coating is abraded. It's not dirty.

- I heard the inside of the collimation cap should be shiny, is this true?

Does my DIY collimation cap look okay? The cap itself is 4.5 cm and the hole is about 2 mm.

I did test the cap on my scope and this is how it looks through the hole:

As you can see, the white ring is a bit off-center. Is it necessary to correct this? If yes, which screws should I use to make the corrections? The screws on the left side?

This is how the back of my scope looks like: