I've got repro from DSS and they are very good.
The way I clean them is remove any surface rust with hammerite rust gel first.Then I have this towel belt from a sacrificed bathrobe on which I put a generous amount of Autosol on, I stand on one end, holding the other end tight and rub each grove up and down until it runs black. Then repeat with dry end of belt. I eventually restored the originals like this, mixed them up and I can't tell which is which anymore.
