Parker 20 gauge SxS, lever will not move to open gun
 

I have made several parts to regain safety and trigger function. I cleaned the gun well and lubed. I reassembled the gun but now I cannot move the lever to open the gun. I am new to Parker’s and one the design is good but without any manuals or even schematics making parts is make and try.

It sounds like you'll have to remove the trigger plate. If there's an interference of the safety, and sears, then the rod, pushed back to move the safety back, can not move, preventing the top lever from rotating.