Could anybody please tell me how to keep these little blighters in situ. Every time I cook something and clean the smev unit one of them pings off. They don't seem to sit very snuggly in the hole. I was wondering whether the conversion company I used have got the wrong type if screw underneath. They've used a dome head self tapper. Would a countersunk flat head give more space for the rubbers to sit properly. I just tried a dab of glue to hold them in situ but the damn glue seems to have swollen the rubber and they are too big now. Just ordered some new ones so I'm interested in how people have fixed theirs in.