How to remove a round tumbler lock on the basement door?

If the key worked before, spray silicone into the opening first. If that doesn't work you will have to drill out the center.

All the locks I have ever seen look like this... This uses the infamous CH751 key... You might try the same key in another basement door lock to see if the key has a problem... Unless changed out its possible all keys are the same...



If this is what you are referring to then you have to get access behind them and remove the large nut.

Perhaps you can open the other side of the pass thru compartment and craw over to this door that is locked...

Also some 5th wheels mine included has a small dirty clotks drop from the bedroom hallway cabinet floor that a small person can craw down into the basement area. You may have to look at this as well to gain entrance behind the lock to remove the big nut...

Roy Ken