Try our new info resource - "Aladdin's Cave" (Main menu)Just added a separate link to Ash's Dropbox thread (shortcut)
Presumably brake arm and it's pivot are free to move, that's what makes the caliper action independent of the fork rotation. Spindle needs to be clamped fully with the clamps fitted in correct alignment too. They are usually arrowed for direction. Fork bracing is a myth in my view, the "brace" on a mudguard doesn't remotely have a load line that can help. It's just to competently hold the mudguard and prevent that from getting near the tire.They where obsessive about bracing in that period, and completely illogical in making aftermarket rubbish to sell.