It's quite expensive, the replacements D2 or D3 series. I don't know why....
Sometimes because of its new old material even expensive than a second hand camera, totally nonsense.
Seems are very similar, the replacements from D2 and D3 series, it's totally true.
But in the other hand D2 series second hand now is very low price, my advice is buying a second hand camera with good cosmetic aspect about 150- 250$ easy to find good one and use the old one with no worries about more damage.
Other cheap preventive solution, it's the easycover silicon protector, I use it in my D4, and it's working quite well.
Protect my camera from sweat and temperature, that causes the problems like yours.
I know I reply late, I hope you read it or someone with the same problem read it the easycover I know it's a bit ugly sometimes but really works.
Lupe
https://www.amazon.e...,aps,134&sr=8-3