George wrote:

We've had trouble with a couple of deadbolts getting hard to operate.
I've fixed this by taking the lock apart, and squirting graphite into
the 'slider' mechanism. This works, but the fit is snug, the graphite
seems to have a little difficulty getting to where it needs to be.
Plus, I end up with black powder on everything.

Can I use something more liquid for this - 3-in-1 oil, or silcon
spray, or something?

Thanks,
G

A locksmith told me some years ago not to use graphite although he didn't
elaborate on why.

Are the locks hard to operate with the doors open as well as closed? If the
doors are shifting out of alignment over time the difficulty might be due to
the bolt dragging on the strike.