James
The wires have 3 different size lugs attached to them and on the terminal block there are 3 different sized screws that correspond to the lugs, so large lugs are held on by large screws etc.
So in reality it should be easy enough to remove the wires and clean to your hearts content then re-assemble.
Maybe you could group the wires on each terminal before removing the screws.
Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto