If your handy enough or feel comfortable doing it go to your local hardware store and get a hole saw that is the same size as the inside ring of your hygro. Find a good spot, usually the lid and mount yout hygro from the outside so you can read it without opening the lid. I have a humi that I will be doing this to shortly, maybe today and I will post some pics! Or if you want to send me an e-mail and I`ll send ya a step bye step with pics.
rck_1athotmaildotcom