On further study of the voicebox, it became evident that to remove the belt,
the other half of shell would have to come apart at the split line. Simply
prying apart is difficult, so it became necessary to push the anchored feet
through the battery compartment with a thin punch or the jewelers screwdriver. Exercise caution, because it's plastic!!
Once that came apart, I was relieved that a whole bunch of guts didn't fall out.
The only thing that rattled loose was a plastic bushing where the motor spindle
was mounted on.
Another commenter said that there was a screw holding the speaker to the stylus. Well, I didn't see any such clip. The speaker simply swivels away as shown on the next post.