Removing broken key from Uhaul Disc lock

[Oatmealer]

I have this Uhaul disc lock that is several years old. It was used outside in the elements for 4-5 years to lock up my grill and propane tank, so it was in rough shape. I purchased a new lock and had been using this one was a practice lock after I cleaned it up. Last time I practiced with it, for S&G's I put the key in the keyway and tossed it into my box O' practice locks. I grabbed it today and tried to remove the key. It was stuck. It would rotate the cylinder just fine, but the key would not come out of the keyway. I wiggled it and jiggled it and sprayed it with lube. I knew what the outcome would be when I grabbed some vice grips to try and force it out. The key obviously broke off in the keyway.
The key wouldn't come out when it was intact, so now the broken tip will not come out with an extractor. I'm guessing it has to do with the safety feature that doesnt allow the key to be removed until it's locked again. This is just an old practice lock so I'm not concerned about it, but I have a question:

How does the mechanism work that retains the key when in the unlocked position? Is there a way to manually release it with a probe or pick in tandem with the key extractor?

If I can't get the key out, I plan on cutting away the body to salvage whatever can be salvaged and learn a little more about it in the process.

Thanks!

Link to image below:

http://i.imgur.com/ySZ90vC.jpg

[Mighty]

If it is a pin tumbler, then when the lock is turned (unlocked position), the pins will have no bible to spring back up into. They would be stuck against the inside of the cylinder. So when you try to removed the key, instead of the pins sliding up and down the cuts of the key, and into the bible chamber, they have no where to go so they hold the key in place.

Edit: If the non-key-stuck pins are mobile, I would try to rotate it into the locked position and extract the piece from there, if you can get them moving again. I doubt you will be able to remove it otherwise, but I could be wrong.

[Oatmealer]

If it is a pin tumbler, then when the lock is turned (unlocked position), the pins will have no bible to spring back up into. They would be stuck against the inside of the cylinder. So when you try to removed the key, instead of the pins sliding up and down the cuts of the key, and into the bible chamber, they have no where to go so they hold the key in place.

Ahhhh I gotcha. So, if the lock is locked, the key not coming out might have been a problem with the key then? Or a damaged pin?

[Mighty]

That would be my guess, but hopefully someone who has experience with this lock will be able to give us some insight

[billdeserthills]

Many of these disc locks have a drain hole on their rear side, that you can insert a straightened large paper clip into.
That will help to push the broken piece out the front, you will also have to reach inside and press the pin tumblers
up, to make room for the broken piece to slide out. Many repairs in locksmithing require a third hand, if you have a vise
to put the lock into it could make this much easier.

[Oatmealer]

https://imgur.com/a/OHeO4

I figured that I had nothing to lose, so I cut it open. I'll remove the rivets tomorrow.

[Oatmealer]

http://i.imgur.com/AnUSZS4.jpg


Update

[Mighty]

Most of it looks OK, though a little worn, but you were still able to turn the key, so the pins were still at the right heights. Was that bent spring holding the key in somehow?

[Oatmealer]

Most of it looks OK, though a little worn, but you were still able to turn the key, so the pins were still at the right heights. Was that bent spring holding the key in somehow?

I believe I bent the spring when I attempted to pull the key out with the vice grips. Looking at a close up of the keyway (before I took the cylinder apart), the shear line is plainly visible. I think pin #1 may have been the initial issue. (Image below) I could be wrong, but I found it strange that I could see the shear line when I zoomed in.

http://i.imgur.com/35q81tl.jpg

[GWiens2001]

Looks like with the short key pin, they probably also had a short driver pin. So when you turned the plug, the spring got caught in the shear line between the plug and cylinder.

Gordon