Stupid question…..

I get a little bubble of ink that comes out the bottom

Do you mean out of the tip?
does it do this while it is running?
what kind of tip / needle configuration?

The needle looks to be lined up in the center of the tube

If you are using round tip – and needle –
I have to recommend that you use Diamond tip – and the needle will not be in the center of the tip
If you mean the “needle bar” is lined up –
you can always know for sure if you use a line-up tool… Pulse tattoo has one
its like a metal bar looks like a pencil – and has a notch in it.
you stick it in the vise hole, and the a-bar nipple slips into the top of the alignment tool – will get you dead center.

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Also, a little ink bubble is not a big deal –
might also mean wrong size needles for the tips?
could be a ton of things –
hope that helped out a little –
ask your mentor too
and check out the book.

rubber bands? Is it loose?

Maybe try bending the needle bar so that it rides on the bottom of the tube?

does it spit ink? if so then turn it down, if its just dribbling out or making blobs slowly then i would’nt worry about it. i get ink all over my middle finger from that slow drool of ink.

I think you need to try another spring for the machine to work.