Here's a quick technique for getting rid of 99%+ of the primer.
-Blow through the cart end of the new atomizer pretty hard, until no more primer juice comes out.
-Fill atomizer with cheap juice, or pure PG or slightly diluted VG. This time blow through the battery threading side until all the liquid comes out. Repeat this 3 or 4 times, alternating blowing it out both ways (screw end and cart end) until the liquid coming out is completely clear.
-Put a filled cart into place in the atomizer, along with a drop or two of juice, directly on the wick, and give it a good 20 minutes, at least, to absorb the fluid. Then, cautiously at first, give it some quick test vapes to make sure the atomizer is good and saturated.
-If the test vapes go well, gradually take longer vapes, making sure your atomizer isn't running dry.
-Vape away!