So looks like I have to replace my heater core

thanks alot guys. ive poked around there alot and i think i can see most of the clips. one more quick question i have is this.

the reason i think i need to replace it is the telltale coolant leak from the box however i noticed that it is not constant. its not even most of the time. it only happens every once in a while and it stops when i get going and usually doesnt start again. could this mean that i dont need to replace it after all? i checked the hoses where they go into the firewall and dont see any leaks there. is what im describing a normal occurance when the core goes bad or do i need to check something else.