Well, at least you know it's working for sure now - that's good. The chances are very good that old Provari battery is quite low-power as compared to the 20A CDR cells commonly used now.You were right my friend. On a whim I tried a battery from my ancient first vaping machine (a Provari) and it actually worked and fixed the problem; now it works a treat. Probably should still get a new battery since I imagine they last longer and maybe deliver a bigger hit also but Im pretty chuffed anyway. Thanks dude
It'll likely be OK for powering those high-resistance coils at fairly low wattages in your Russian 91%s, but to vape anything more powerful you should definitely wait until you get some decent new batteries - you should get them regardless, actually.