I never use new tanks straight from the box without a close scrutiny & clean-up. I find a tray to contain the parts then dismantle the RTA down to the base, body, cap and glass for close inspection. No need to remove any O-rings.

I then ...

• confirm all parts are present & in good condition, working the terminal screws to free up if necessary.

• check for tiny fragments of residual metallic swarf, often only visible using a small x40 magnifier (highly recommended). I've found varying quantities of this on most of my tanks (knockoffs & genuine). I'd recommend removing all traces of residual matter (see pics),  aiming to eliminate chances of nasties getting into your body 

• Also, inspect the 510 connector and if needed, aim to get that smooth and polished too, which'll minimise wear on the mod's connector and reduce resistance fluctuations.

• I then suggest giving the parts a good wash/brush in isopropyl and thoroughly drying out. Isopropyl won't hurt O-rings so pointess to risk damage by removing them.

Wait until the isopropyl has dried thoroughly before continuing

Reassembly

On some tanks the cap ring and other O-rings can easily come adrift which may cause them to become pinched upon reassembly.  If any are like this I suggest removing, putting the slightest smear of cyanoacrylate glue in their O ring cutouts and refitting the rings before drying.

I also suggest lubricating easily-accessible O-rings with PG/VG (no need to remove rings), which'll make pinching less likely.

Confirm the tank goes together smoothly, without crossthreading.  Careful not to over-tighten, extreme tightness is unnecessary for sealing purpose and risks O-ring damage and difficulty in disassembling 

If the 510 centre pin is screw-headed, ensure it isn't loose. For flat-bladed driver pins, I suggest using a well-fitting screwdriver - one of your own rather than sub-miniature blue handle "cracker toy" drivers that are often supplied with these tanks.