Why is my trigger coming back slowly once pulled?

Just some random cheap amazon water gun that has a moving slide that's supposed to move with each trigger pull. However that's malfunctioning because the trigger resets really slowly after each pull, meaning rapid fire shots don't cause the slide to move all the time. I've tried cleaning the pump out with soapy hot water but nothing's worked. Any fixes or should I just cut my losses and trash it?

Should probably also mention the only screws I could take off just removed the slide, no direct access to the pump. I'd rather keep the gun as it's a neat little prop, but it's not too expensive to throw away.

Photo for clarity.