Tom, Moss lists a top entry cap for the 25D, P/N 163-815.
If you want to keep the side entry cap, just get a generic 7mm wire set, and cut off the ends that would normally load into the top, and install in the old cap. An 8mm wire is too big to fit into the holes in the cap. I run 8mm wires on one of mine, but I reamed the holes to 8mm to fit.
I usually make my own plug wires, and found that the best way to go with the side entry cap is to use copper core wire, rather than the fiber strand core. The contact screws don't work well with the fiber stuff.
Jeff