Innokin VTR firing issue

IMy brother gave me an iTazte VTR today as he has gotten into mechanical mods. He told me it had some issues but still works w some hassling. It seems that sometimes when you attatch a tank to the mod it won’t fire ( and green light stays on for a few secs ). If I wiggle or move the tank around a bit, it will fire. Not complaining as it was a free mod. But I would like to use it along side my MVP. So, anyone heard of this issue and is it fixeable? Thanks in advanced everyone. I appreciate any insight.

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