Spade terminals are 50% too thin - they will fall out, or have poor contact depending upon the residual spring strength over the last 30+ years.
Think think tweeter destroying intermittents in time with the bass.
Several threads on alternatives, including the cheapest possible "ghetto" fix that's surprisingly effective. ugly but functional.
edit:
nah, THESE were the ghetto plugs: (specifically for the zero budget person)
ugly as sin, but quite functional
http://www.audiokarma.org/forums/showthread.php?t=273908&highlight=ghetto