Hi Ian.
I changed all the belts on my Super 7 when i bought it a few years ago. From your model year i would say if you have a clutch it will be the early type. It is a cast iron horseshoe type. It expands onto a drum. I have no experience with that version other than knowing from friends machines that.
The cast iron ring is very brittle & can break in half if not looked after. Also with mine not having that type of clutch , cannot be sure how easy it is to strip.
I think i do have a ML7 manual in PDF format. If i have you are more than welcome to have a copy.
With that you can see every component & work out any problems before stripping down.
I bought genuine belts from Myford & have never had any problems with slipping at all.
Steve.