I am having a problem with the rubber button hanging up and it appears to be the rubber is catching on the metal front panel causing the button to stick. I tried cleaning it with alcohol and it seems like it got better until the alcohol dried out then we had the same problem. I tried a light coat of vaseline and it seemed to get better. My question is, what kind of material is the rubber? Is it silicon based? Should I be using a silicon based lubricant?