Don't use WD-40, it will just cause more dirt to accumulate. Get some powdered graphite and use that on all your locks. It is the preferred lube for locks. I have used it on my C14's locks since I got it and have had no issues. I use the stove knob key for everything, it slides in and out very easily.
+1
Graphite, powdered or spray is the best thing for locks. WD-40 is only a temporary fix. You can clean w/ WD-40, then lube, but even then other cleaners might work as well or better.
As to the bent stove key: Insert key fully, then turn. If you meet any resistance, you're doing it wrong, or their is a problem. With a hammer, anvil, and perhaps a punch, it is usually possible to straighten a key almost back to original specs. If you are as impatient with the hammer as you were with the key when you bent it, if may not turn out well. I've been using the Ignition key in the bags and tank for almost 5 years. I learned my lesson the first time I bent the key, and it has worked fine in all 5 locks since straightening it.