You should throw the Pump and Tank in the garbage with it.
You either have air leaks causing you to lose prime or that two inch casing is allowing air in around the screen. I'm not too clear on what you did.
When you wash in a well like you did, the two inch is usually pulled up after the screen and pipe is put down. I'm guessing you just put these things in without even test pumping them since they are at differing depths. This is another no no.