Starter not engaging
 

This same thing has happened twice in the past week. Turn the key, I can here the fuel pump but the starter does nothing, not even a click. I've checked the battery and it is fully charged. All the dash lights come on etc. but nothing from the starter. After repeating over and over still nothing except for the fuel pump running. After waiting a little while, go back and try again and it fires right up. Could the starter be bad? How can I test? Or is there something else that could be on its way out, CD Unit? Both the starter and CD Unit are original. Car is 1977 with a 2.7.
Thanks.