It almost certainly can be fixed.  I would think that there is most likely damage to the trigger sear or  the hammer.  I have had something like this and discovered that someone had improperly worked on the hammer.  

To properly diagnose,  the hammer and lower tang will probably have to be removed and examined.  

Gunsmiths that work on these guns will probably do this repair for a fairly reasonable cost.  

If need be, replacing the parts would likely correct the problem too.  But, best to examine the parts to see the cause.