And you understand you do not actually need more carts? Those carts will physically last near forever. You need eliquid. You can push up the juice cup by sticking an unbent paperclip in the mouth hole of a cart, add some eliquid into the stuffing (not too much because you have auto batteries so they are easy to kill or damage with juice leaks), make sure the stuffing is near the top edge of the juice cup, and then get the juice cup back down into the cart without pressing on the stuffing,
The e-Health/M40x have very very tiny juice cups, much smaller than the outside size of the filter-look cart. It is one of the smallest ecigs and holds very little juice. I started on M402 manual and upgraded to M401 manual and then within 4 weeks bought and switched to other ecigs.