If it's dry in the centre then you're probably making the wick too tight, for a 2.5mm dia coil you need a strip of muji about 4mm wide, peel off the outer woven layer on each side then twist just the very end into a point, When you pull the wick through your coil there should be just a little resistance, this is how I wick coils and I almost never have any trouble with them.
You might find this a useful illustration - Wicking starts at 17:30 ish
Thanks for the advice I will give that a try! I don't want to quit as I'm quite enjoying making the coils. Guess it's just a learning curve. You guys are always so helpful on here and never judgemental.