I have two Coppervape Dvarws
SKU 9646336 one has been used daily for just over a year the other for 11 months.
I now use the std. 1.2mm inserts but also used the 1.5mm for a long time.
I bought these oval holed chimneys for both of my Dvarws and have used them for 11 months. My Dvarws do not leak when using either these or the original chimneys. These chimneys do give a slightly "wetter" more flavour filled vape imo.
I use 28g. SS 316L coils with an id of 3mm. my e-liquid is VG based with 15% de-mineralised water.
Old photo:

Why not try a Coppervape Dvarw v1
SKU 9646336 with the original "chimney" (chamber) and then tell us if this has actually solved your problem?
Edited on 8/17/2019 at 9:02 AM. Reason: img-link