Hello, just joined, this is my first thread and a curly one.
I just received a Scuba Dude, Vostok 21j I bought from Ukraine via eBay and it is reading 25,200 then 21,600 and 19,800bph on the phone app Timegrapher. Sometimes if I first put it on another Vostok so the timegrapher reads 19,800 then without pausing it I put it on this one it will read 19,800 a while then jump down to 10,800.
It's running way too fast as well. I used the MgntzdWatch app and it is in the magnetised zone but only…

Vostok 21j reading 25,200 then 21,600 and 19,800bph