Thanks for replying rtbcomp, but I had previously tried the links list of manuals and Mini-Mig was not among them. Yesterday I received an email at last from Clarkes International customer service after two emails and two phone calls from me. They didn't have a manual but could tell me that the Mini-Mig had a max of 90amps and a minimum of 25, so there you are,... if anyone else was interested!
I'm guessing it's an older Clarke. I had a search of the forum and while it's been mentioned nobody has mentioned any specifics, so thanks for yours. Older welders tend to be nicer than cheaper newer welders so worth working with it.
For interest could you post a photo, and do you know the approximate date when the welder was made?