I have a James Products Ultra 7000 ultrasonic cleaner which I’m told was the most popular one in the UK. I don’t think it’s available now. It cost around £35.00 when I bought it maybe ten years ago.
I use it with water and a German cleaning solution that comes highly recommended. To be honest, I don’t find it all that useful and I don’t use it much. I would rather use fine brushes and cotton buds to clean the feed and section. I wonder if it actually achieves any more than a quick soak with cleaning fluid would do. Where it is more useful is with oxidation and rust remover on the odd occasion that I come across an accommodation clip with a little rust. Again, it’s possible that it is the rust remover rather than the ultrasonic process that does the job.
My cleaner might be more useful if it could be set to run for longer periods but the maximum, so far as I remember, is five minutes, then you have to re-set the thing. From past experience I can say that five minutes does not make much impression on a nib and section unit that is thoroughly clogged with old ink. Perhaps a 30 minute setting would be more effective and convenient.
The larger ones used for carburettor cleaning certainly do a very good job but they are quite expensive and have a large footprint. Honestly I’m not at all sure that these small ultrasonic cleaners are really a necessary part of the restorer’s toolkit.