WE M9A1 hammer issue

[HSCtheta7]

Evening one and all,

 

Bought a WE M9A1 off here a while ago, the basic first-gen model. Recently I've been having an issue with its hammer - if I rack the slide to cock the hammer, most of the time it won't stay cocked and will go back to its original position when the slide returns to battery. It's only if the slide returns under its own power - if I return the slide slowly, the hammer stays cocked. And if I manually cock the hammer, it stays cocked like it should.

 

TL:DR - my hammer won't stay cocked when you rack the slide.

 

Any advice on how to fix this issue would be greatly appreciated. Getting a bit annoyed with firing a DAO pistol right now XD

 

Thanks,

Theta