Try pulling the inner cart and dipping, see if it goes away.
Remove inside cart on the M401, using a safety pin or paper clip.
Put small amount of e-liquid in soda cap or similar (just a few drops).
Put atomizer wick (the 'steel mesh') down into the liquid drop, and let it absorb for a few seconds.
Put mouthpiece back on *without* inner cart/poly, and take a few drags - still taste funny?
Remove inside cart on the M401, using a safety pin or paper clip.
Put small amount of e-liquid in soda cap or similar (just a few drops).
Put atomizer wick (the 'steel mesh') down into the liquid drop, and let it absorb for a few seconds.
Put mouthpiece back on *without* inner cart/poly, and take a few drags - still taste funny?