hardened ink on type

Have you tried a good hard rub with a cloth well soaked in type wash?
A soak in a solution of TSP followed by a brushing with either a type brush or the standard worn out toothbrush will work.

Any ink remaining will not harm the printing.

the TSP is probably a pretty good idea. But if that doesn’t work, try carburetteur cleaner from the car parts store. It’s pretty mean stuff, and certainly you should take precautions, but it will remove just about anything from metal.

depending on whether this is wood or iron type, I would first suggest acetone or rubbing alcohol. Both of these solutions dry out wood type, however, and would be careful not to damage the type itself.

definitely type wash! since it is type, you can always soak it. I have a bunch if you need someone to clean it for you.

Carb cleaner or brake cleaner should do the job, but I’ve had some success by soaking in paint thinner for a couple of days then rubbing with a toothbrush & cloth.

If you set some clean pressboard or plastic in the bottom of the pan, you can put the type in face down and use less solvent.

Carburator cleaner is better not smelled or digested.
Dried ink can be cleaned with pure gum Turpentine, soak, give it time, wipe, done. The Turpentine also doesn’t dry out wood if Woodtype.