I replaced all four on my Hunter 40.5 for the same reason. I used a heat gun to soften the adhesive. This also broke the glass which I removed a piece at a time using a paint scraper. When they were all removed, I removed as much of the adhesive as possible. I can't recall if it was adhesive remover or acetone. In any event, the final step was acetone. I had a glass shop make new mirrors with some bevel and rounded corners to my measurements. Per their recommendation, I used a specific mirror adhesive to install them. Get some inexpensive glass installation suction cups for mounting them. I used large amounts of wide masking tape to hold the mirrors in place for a few days. Then I filled around all the edges with a color-matched latex calk to make sure no further moisture got under the mirror. That was probably ten years ago and they still look good. Good luck.
Any thoughts on where to get a replacement mirror for the head? Ours is starting to corrode and I've been asked to get a new one. It's the older version, that drops down, not the newer two piece slider. Catalina Direct doesn't seem to carry them. Haven't called Catalina Yachts yet.
