Lilibet, WELCOME, I think that one (RN4072) is an 801, I'm not sure. Read some of Jim Davis's Threads in New Member's, I think he covers this pretty thoroughly. Moleman, I think you may find some helpful info there regarding your DSE-801 also, they are I believe compatible parts.
The most important thing to transition in comfort is to 'find' your comfort level, a well-working PV, plenty of supplies, and a
juice with high enough nicotine to keep your cravings at a minimum, and proceed with confidence this will work. Always have to remember to "pack the diaper bag and remember the baby", so you aren't going to be stranded somewhere with a dead battery or empty cartridge.
I started with 24mg/ml juice (I was a HEAVY smoker) and even though I was so hungry I could eat a road kill skunk, it kept me happy enough to leave the cigarettes alone from the start. (Nice!) Since I started I cut back my nicotine by 25% twice with NO WITHDRAWAL, now down to 12mg/ml juice and still very happy and content. Have also cut back on amount of juice I use, now at about 2ml per day, some days less, some days more depending on stresses. That's an enormous accomplishment for me. Oh yes, hunger and the 'jittery' rush of energy are standard withdrawal symptoms, but it is very manageable if you put your mind to work. The idea that you no longer have everything smelling like an ashtray is enough to keep you VERY happy and breathing free!! And I also did manage not to eat any road-kills skunks, kept my weight from ballooning just knowing it was part of withdrawal. That hunger lasted a couple months, so you all know it does take some time.
And remember to DRINK LOTS OF WATER, PG and VG in the nic juices are a little de-hydrating to your mouth throat nose and lungs and facial tissues, also increase your fresh veg's and fruit lots of anit-oxidents to help your body cleanse itself of all the toxins and junk. Extra fiber will keep you from experiencing digestive upsets which can happen, some people actually have problems with ........ for awhile.