Need help with American series 260 and 200 padlocks

[candado3]

I have a number of NOS American padlocks from the year 1978 all but one have keys.
They all open and work well except the series 260 padlock for which the key will not turn.
I tried soaking it in penetrating oil for a number of days, tried WD-40, sprayed inside with lock saver, cleaned with brake kleen etc to no avail. I tried rapping the side of the lock as I turned the key as I did on the series 200 lock mentioned below but this did not work on this lock.
I have a series 200 padlock, a smaller version of this lock which was also stuck but after soaking it and then rapping it on the side many times as I tried to turn the key, the key slowly but surely turned and I was able to open the lock, It opens fairly smoothly now but I wanted to dis mantle it and clean the insides. The problem with this idea is that the screw inside the shackle hole will not turn no matter what I tried and I don’t want to strip the head of the phillips screw.
I need some help in figuring out what my next steps should be to rectify both these situations.
I have added photos of the series 260 padlock.
Thanks in advance

[madsamurai]

That's a nice find... For the one(s) that won't turn, you might try soaking in a sonic cleaner with brass cleaning solution like Hornady One Shot or something similar... that might work to break up any corrosion in the plug that's causing the core or pins to stick.
For the retaining screw, you can try an old gunsmith trick and put the screwdriver into the screw head and then give it a couple taps with a hammer to break the thread binding, that will often release old stuck screws. If that doesn't work, the next easiest solution I know is to just drill off the screw head (use a drill press if you have one to avoid damage to the lock or your hand) and punch the rest of the screw and retainer out of the bottom, then replace both with new parts.

[candado3]

Thanks for the reply.
I don't have access to a sonic cleaner so that is out of the question.
I found a few links to a homemade alternative to "Hornady One Shot" that consists of water and vinegar 50/50 and a drop or two of dawn dish soap. Do you think that soaking the lock in that solution without the sonic cleaner might work? What about heating the solution with the lock soaking in it"

I did try to tap the screwdriver with a hammer both just holding it and while trying to turn the driver but that did not work.
I was thinking that I might have to try to drill out the head of the screw but was hoping that there might be a different solution.

[tpark]

Can these ones be bypassed? Some earlier American padlocks could be bypassed, and that might work even if the core is jammed.

[candado3]

Just an update.
Isn't the internet a wonderful place.
I looked up homemade ultrasonic cleaners and found a few suggestions of using a palm sander.
So I clamped an old palm sander in a vice upside-down put the lock in a plastic jar with penetrating oil and duck taped the jar to the bed of the sander. Ran the setup numerous times over the next 2 days at 10-15 min intervals.
Tried the key this morning and to my surprise it popped open easily.

[madsamurai]

Awesome! The hand sander is a great solution... I love repurposing tools for things they aren't meant to be used for. Well played.

[tpark]

That's freaking awesome! Glad you got it open.

[Barracuda559]

Hi, I just found this thread because I'm having trouble with a 260 I'm trying to help someone restore. Can you tell me if there's any bumps at the top of the chamber you'd feel with a pick besides the key pins? Dragging my pick from the back wall to front (no tension). I feel a bump that feels like a frozen pin but then a small gap and then I think 5 pins. So what gives? I could be wrong the pens are really hard to count with all that crud and light spring tension.