Chickadee in Woodpecker hole

We have a very dead tree in the yard with lots of woodpecker holes, some small and shallow, some large and shallow, and a few just (almost) right! There is a Chickadee working on one hole getting it cleaned out to it's satisfaction. You can hear it working inside chipping away at the rotten wood. The tree is so rotten I hope it does not fall before the chicks fledge. Here are a few photos. First, the hole.

Next the Chickadee.

This is the Chickadee with chips in it's beak from hole cleaning.