Hoping for some help here with my new 510.
Does the harsh burn on my
throat mean it is time to top off?
Probably, or it could be primer if a brand new atty. You generally should just pay attention to when vapor production and throat hit decreases, then top off, or better, refill (via syringe, etc) or swap carts.
About how many drops to refill a 510 cart?
Dropping from the top won't really do a good refill, without the 'straw mod' (search), or waiting a while, or inserting a dental pick, toothpick, something to allow air to escape from the bottom. You can certainly remove the poly fill, drip ~8 drops, re-instert the poly, then top off from the top, or just 'add a few drops,' or refill completely via syringe (or the 'precision oiler' pic someone posted), from the bottom of the cart up.
A fresh, never used blank 510 cart takes ~ .5ml of juice. Refills on used carts, depends, from .25ml on up in general.
How do I know if I over-filled?
It'll pool over the top of the cart. You want the poly to *just* start saturating at the top, so if you press it, you'll get juice. Compare to an original filled cart for comparison. It may also leak/squeeze out when inserting the cart, if it's really overfull.
Should a new cart gurgle?
usually a bit...but you may have also overfilled a bit, too. Mine usually gurgle for the first half dozen or more hits.
When I drop liquid on atomizer and draw it makes a sizzle sound for the 1st few puffs, is this normal?
Dunno, I don't usually drip, no need to on the 510, IMHO. If you've flooded the atty, it may gurgle but take longer, as well, it's flooded. A few drops should still give a bit of sound, just like a full cart. Someone with more experience dripping should answer this one..
Anything I can do about the leak between cart and atomizer, other than duct tape?
Huh, never had a problem with leakage, unless I grossly overfilled the cart, with liquid running down the side, then still stuffed it into the atty..