Daewoo DP51 FTF/FTE Issues

I tried this in r/gunsmithing but I think that place is a dead zone,

Anyway, I recently bought a Daewoo DP51 9mm pistol. I was intrigued by the "Triple Action" aspect, and it also felt pretty good in my hands.

Anyway, I went to the range yesterday and was disappointed with numerous (30-40%) FTF and FTE malfunctions. It was completely unreliable. There were times when I would have to pull the trigger 5 times (double action) for the round to fire, and other times I would have to manually work the action to eject spent casings.

What could be causing these malfunctions? Visual inspection of the pistol showed no defects, though I am not an expert. I was using S&B 115gr FMJ, as well as herter's 115gr FMJ which is essentially the same ammo. I believe it could be weak springs as these Daewoo's are getting older. If so, which springs should I look to replace?

Any help is greatly appreciated. Thank you.