Changing A Screen Door Lock

Attachment 530439

I need to change a screen door lock, the locking bar is in the extended position (although the door isn't locked) and I don't have the key.
The youtube videos say slide a knife in the side of the thing to manipulate the locking bar so you can get it out.
The lock is a tight fit, all I could get in there was a feeler gauge but I couldn't get the locking bar to move - it could well be jammed.
Is there a trick I don't know about or is it time to get hooligan with the drill & dremel?
Cheers
Smidsy

There was a thread on here just recently about the same or similar problem - perhaps do a search for it.

take the 2 sides of handles faces off and use a thin lock pick tool in there to slide the lock cam upwards and should come out, ive done dozens, some harder than others but never failed. longest one has taken me around 10 minutes.

As above, usually easy but
I admit to fighting with at least one before I got out the 4" makita angle grinder with thin metal disc and sliced the tongue/locking bar off the lock.
Remember to keep the pin depressed above the lock tongue while attempting to slide the cam up or down depending how the lock has been fitted.

If you do not have a key, and want to replace the cylinder, unscrew and remove the handles. Then using a pair of multi grips, hold the cylinder and twist until the cylinder breaks and can be removed. You should now be able to see inside the lock and at the front there is a block that needs to be slid either up or down to unlock the bolt.
When fitting a new cylinder it is necessary for the bolt to be in the extended position.