Pull out water well pump

[zyin]

Hi friends, we have a 4" deep water well, I noticed when the pump is on, water leaks from the well cap. I opened the well cap, tried to pull the drop pipe and the pump out, but it seems that the pitless adapter somehow will not disengage, the drop down pipe did not move at all. I believe we had imposed at least 500 lb lift up force already, nothing happend.
I'm afraid that using further larger force might damage the pitless adapter on the well casting wall.
Please provide ideas how to solve this problem to pull the drop down pipe and the pump out. Thanks!

 

[Reach4]

Do you mean you have a 4-inch casing?

What kind of pitiless do you have? If you don't know, post a picture of what you can see with the cap off.