No matter how much you spend on your new water gun, it will eventually start experiencing some problems. But that doesn’t mean you have to abandon it and purchase a new one! Many of the common issues can be very efficiently and cost-effectively fixed.
If your gun is leaking, it might just be that the spring inside isn’t being depressed sufficiently or that the trigger has fallen off its groove. Try quickly pumping and pulling the trigger release in quick succession and this should on most occasions snap it back into place.
If on the other hand, your pump seems to be jammed, try lubricating it with a silicone spray or a bit of vaseline. Either of those should do the trick, but if not, you might need to quickly unscrew your rifle and just check that there is nothing internally that has become clogged.
If your water gun cracks a little, try sealing it with a bit of epoxy putty which is water-proof and should do the trick and give you several more months of fun.