"patrick j" wrote in message
al.Net...
Hi

A mortice lock on an external door which I hardly ever use has become
seized. I bet the problem is corrosion.

Anyway I've found out because now I want to use the door

I'm wondering if anyone here might be able to assist with some suggestions
to free up the lock?

Thank you.

Sometimes the door or the frame distorts jamming the lock bolt against the
edge of the keeper/striking plate.
Try pushing/pulling/lifting the door as you turn the key.