Last year I bought a cookbook at a used bookstore. Inside, some poor woman had
forgotten clippings of traditional Jewish dishes, including one for cheesecake.
This very old, faded newpaper clipping stressed 2 things over and over again:
1. Do not open the oven during baking
2. When the cooking time is finished, turn off the oven and allow the cheesecake
to cool inside, still without opening it.
I tried this with the recipe for which it was meant, and it worked! It even
worked on the Italian cheesecakes which I made last Easter.
All the advice you've been given already sounds good, maybe this will work too.
G