Cornwall new terminals

I have a pair of 30 year old Klipsch Cornwalls. The terminals on the back are very small and I want to use large speaker wire. So I need to install new terminals. I have never messed with my speakers before, and I want to get myself ready before I start. I have the following issues. How are the wires inside the box attached to the terminals: soldered, crimped, detachable coupling. etc? Is it necessary to take the back off the box, or can that somehow be avoided? If I must take the back off: is there a gasket that I will need to replace; is there any other maintenance I should do while I am inside. Additional guidance or cautions would be appreciated.