Hey Stanley,
Yes the Whisper seems to need some help, but putting foam or electrical tape will only be a short time solution, as these materials will compress in time, and you will be right back with the problem.
Use 35 m.m. film or cut some shims out of hard plastic or aluminum for a more permanent fix.
If you watched the P.A. Video you will see that they had this foam tape on there Whisper also ..
I hope this helps you,
Bill