step #1, forget everything TDM said because every last word of it is wrong and applies to other types of carts, not the 510 carts.
Step #2 Take the poly fill out of the cart. This is all you NEED to do to make the cart 'drip friendly' but there is more than you can do.
Step #3, use a paper clip in the hole of the mouthpiece and pry the cap off the end. This will create a recessed end like the filter of a parliament brand cigarette.
Step #4 use the paper clip in the hole of the recessed part and pry that out too.
This should leave you with a cart that you can see clear through on two sides. That is as much as you can strip a 510 cart and it will provide a great easy drag that way.
DW