After 30 + years a natural rubber mount is well past its performance lifespan. That doesn't mean its going to fail, it just doesn't isolate anywhere as well as it is intended to.
It would seem these have served you well, if you can afford it and can find direct replacements that would be a good and relatively easy fix.
If you can't find direct replacements your existing mounts are tall enough to give you a good range of replacements.
$0.02