How to repair cuffs?

[Cepasaccus]

Got these cuffs. The lock on one side is working perfectly, on the other not. I can push back the locking bolt with a screw driver to free the ratchet, but the key does not grip. Any idea how to fix that?

Thanks

[Timothy]

You may have a worn out key or try to clean it out also may have t clean out inside the lock. Otherwise there may be some locksmith in your area know about these cuffs and key....Timothy....

[Richard Phillips]

Are they really old? they look to me as though they recently arrived from Pakistan via a mail-order catalogue.
I suspect a poorly made thread on the cuff, and the thread in the key might not be well-made either. It will be difficult to remove the riveted endcap to dismantle the lock. Tilting the key as it is turned might help it to grip the threaded screw. Otherwise,it might be a paperweight or display item.