Good one! I just happen to secure the top case with only 3 screws as I have to occasionally get in there to massage the pesky C78 pot when it floats and to blow out accumulated dust. I will order the proper bulbs! Edit-where did you buy yours? I can't locate a seller so left a message with Icom. Thanks Bob.The bulb assemblies were $3.98 each two years ago, and I bought two at the time. As you suggest, the rubber base is probably instrumental in keeping dust out of the meter. But it's also effective in ensuring it doesn't become dislodged at some point. You wouldn't want to remove all those case screws again if you didn't have to, would you?