Setting gophers traps and most of the time, when I lift
The cover which is cardboard, the hole trap is covered and hole filled to bottom of cover. What to do?

You mean like this?




Pull your traps and fill in this trap set. Probe and find/set a new trap set in this guy's burrow. Ensure you are "bedding" your traps somewhat in the trap set tunnels. You don't want them loosey-goosey or he will caddyshack you again. If he does, it's time to pull the traps, level all the mounds and wait till he gets happy again (starts throwing mounds again). Don't give this rascal his PhD by continuing to try to catch him the third time.