Stiff door locks -- 82 245D

[Hendo]

I have my dad's '82 245 Diesel.

The electric door locks are extremely stiff; it takes a LOT of force to move them, both with the key as well as the interior plunger.

I was hoping that regular use would loosen them up, but so far not much improvement.

Do I need to pull the interior panels, etc to lube them up, or is there an easy way?

They are stiff enough the electric lock fuse blows when I try it.

Thanks in advance!

-Tom in So Cal