Ive had my SVD for about a year and a half when they first appeared on FT. Way past the warranty. So approx. 3 months ago started getting o.o ohms, wiggled center post up ever so slightly, works again, i use diff. types of tanks and on numerous occasions, again, wiggle the center pin. Fast forward.....last night went to your neighborhood home improvement center etc. and bought a couple of o-rings size 1/8"I.D. (1/4"O.D.)x1/16"Wall
Those are exact numbers on the size of the orings that fit my SVD, Other Mods may vary. Carefully lifted center pin, placed o-ring, not easy (take off beauty ring, it helps navigation)and pushed center pin back in. So far no issues. Original o-rings were pretty thin. This solved my problem. But many thanks goes to a utube video on "SVD center pin fix". So far These size o-rings not only fit my SVD but also my Smok ZMAX; Still my favorite.
Cheers