sorry for interrupting actual discussion.. just to share an stupid workaround for my 510 pin problem, which is working ok:
antecedents:
the smaller bottom gasket is damaged, so the pin (and that gasket) were wobbling (touching the walls) and sinking down; the spring and the broken upper gasket were outside, and couldn't insert them back till ZeroOhm shows us how to take the top cap apart safely (not breaking the ground soldering), if possible.
temporal fix:
inserted a white (soft) silicon o-ring (7.8 x 5.6 x 1.1mm) at the bottom.
inserted a red (hard) silicon o-ring (7.2 x 4 x 1.6mm) above it. it has the right thickness to fit the channel of the pin where the upper gasket was "holding" it (about 1.5mm), so the pin doesn't sink down; it has the right width to fit the walls (~7.5mm ID) and the pin (~4mm width).
the result is a fixed 510; well, it has a minimum tolerance, due to the compression ability of the silicone. it's isolated, the pin doesn't touch the walls (had no shorts yet). it's a bit sunk, so attys with short 510 doesn't make contact (for example, the erlkonigins with no adjustable 510; but didn't try this one when the pin was ok

)
tried 20w, good contact, no shorts, it's working flawless, so won't try to insert the spring, unless i'm sure 100% of not breaking the whole device.
maybe yihi reconsiders their warranty coverage of this issue, and also learns that a satisfied happy customer ensures the company success at medium-long term (warranty, repairs, and qc, are investments, not wastes).
thank you very much, dravell, Nikki (my guardian angel), ZeroOhm, and all who have helped and given love =))