How can I separate these two parts?

[Massey convert]

g8erh8er,​

Thanks for letting us know how things worked out for you.
looking at the top picture you posted, it looks like some green loctite left on the two studs. If it is, that might be what caused your trouble. Whoever assembled it was, they used an excessive amount; when using loctite, you dont' need much.

 

[pmsmechanic]

So now while it's apart would be a good time to grind a pry notch into the cover...for next time.