Hoff,
Pull the cap and remove the rotor. Attempt to move the distributor shaft side-to-side. If there isn't any movement between the shaft and the distributor body, you passed the first test.
Remove the cup. If the spring and plug are gunked up and won't come out, you can unscrew the entire grease cup assembly from the distributor and push the plug and spring out on the bench. Once you remove the assembly, look for the plug. If you don't see it, shine a light in the hole in the distributor to see if it is against the distributor shaft.
Carl
