Yea, maybe it's in place - but I thought mine was, too. You can see the brass base just fine, BUT, BOTH your positive pin (that holds your coil) AND the center pin have to screw into the brass base. I am willing to bet that it is the positive pin that is not screwed into the brass base, or the tiny top insulator (that fits on top of the brass plate) has moved out of place during this ordeal.
On the positive pin, there is an insulator that fits above the brass disc and the larger insulator that spans the width of the base. The brass disc is "sandwiched" between these 2 insulators, the positive post passes thru the top, small insulator, threads into the brass base - holding it in position. At this point, you should still be working looking down on the base. We haven't even gotten to the perceived problem of the 510 connection post yet. The reason your atty won't screw in - or stay screwed in, with a coil attached, is because there is just enough leverage & pressure, (with the coil seated & wicked) from the wick, coil, sleeve, guard & top cap that it is now in place, that the entire guts of your base (that can't be seen) is raised a bit, which in turn, raises the 510 connection. If you do get it connected, then it is bobbing up & down like a boat, inside the base - you won't be able to see it happening, it's all on the inside. Since the brass disc is bobbing, so is the 510 post. Here are instructions (not authored by me) to fix.
SOLUTION: Here is how to fix that problem:
put a small phillips-head screwdriver into the 510-connection hole and catch the center hole of that internal cylinder.
Then I turned the base upside down.
Then, watching inside the positive-pin hole, I turned that screwdriver until I saw the hole exactly centered in the positive-pin hole.
BUT before you screw the positive screw inside its hole, WATCH CAREFULLY inside the positive-screw hole while turning the bottom screwdriver (that catches the brass disk through the 510 connection), you should see somewhere (after many turns) THAT TOP POSITIVE INSULATOR DISK.
Then centre the hole of that insulator disk with the hole of the positive-screw hole and FIX it by inserting a very small screwdriver into the positive-screw hole.
Then rotate the bottom screwdriver until the top screwdriver falls down (meaning it catched the positive-screw hole on the brass cylinder, while mantaining the top insulator disk fixed under the positive-screw hole).
Then GENTLY remove the TOP screwdriver (NOT the one on the bottom, wou won't catch the hole of the positive screw in the brass disk if you remove the bottom screwdriver!! that's because all internal parts have some play in that room) and check (by looking inside the positive-screw hole) if the hole is centred with the center hole of the insulator disk AND with the side-hole of the brass disk.
Then GENTLY insert the positive screw MAKING ATTENTION ON NOT MOVING ANYTHING!
Screw the positive screw.
Then turn upside down the base.
THEN remove the screwdriver on the bottom and screw the 510 screw.
YOu're done! THE POSITIVE-POLE PATHWAY IS FIXED, IN THE CORRECT PLACE AND PERFECT.
This is tedious, but almost a sure fix for your problem. Good Luck. BTW - Make sure during all of this that you don't loose the little spring that your 510 post slides through.
