Other issues to watch out for when food, wax, etc. is attached to the part where there is no letters, numbers, etc.
Putting Away Laundry That Is Still Hanging Around From Before Shabbos. Taking Out Frozen Milk or Frozen Challah for After Shabbos;
the use of a thermometer on Shabbos;
Is a Mouse a מינו נצוד (An Animal People Typically Trap) or Not?;