Hi and welcome. A little more info, please. You mean a Hammer mech
mod? Do you have a clone or an original by Kato? The clones are famous for having a janky live spring in the
tank connector which sometimes goes out. I have heard, but never tried, you can use the spare 510 center pin from a FUhattan to replace the clone two-caps-and-spring assembly in the 510 connector. Also, some people are replacing the button with the button assembly from a King V2 as it has better throw and connectivity. As always, all mech mods need to be kept scrupulously clean, especially where they thread together, to avoid internal resistance.