Thanks for the tips vapdivrr. I was able to fill it successfully after replacing the wicks with larger ones and filling as folkphys explained. Seems to be working well and no more leaks. Only issue is a bit of gurgle and a small amount of
juice in the tip every now and then. Don't understand how a tiny bit of
juice keeps ending up in the bottom of the drip tip because everything is sealed properly but it's no big deal. I just pop the tip off when I notice it and dab with a paper towel.
I have previously tried the fill method you outlined but I was using those skinny wicks at the time and it looks like that's what the problem was. Yes, I agree that the trickiest part is catching the threads when you screw back the base but it's not impossible. Just requires a bit of patience. I'll give the bottom fill method another try on my next fill, which should be coming up very soon at the rate I've been
vaping this thing! lol