A surprise win on ebay gave me ideas...
Suspect handling around Cannock identified and odd problem: the steerer was not symmetrical, the top and bottom faces were around 3 degrees out. Now, I'm no stranger to an angle grinder and using my calipers as a datum (they are the most precisely engineered flat surfaces I have) I set about with dremel and grinder.
Success! The slightly awkward feeling steering was replaced by super smooth turn to turn.
I suspect the constant wear from a too small headset top cup had been the cause. A Shimano 600 from the road spares drawer fitted perfectly and was a good tight fit.
The Tange Switchblades had arrived this morning. They wore their age with lots of surface rust and attacks on the bearing race with a screwdriver and a hammer. More dremel action, some very soft well used wire wool and an hour later, they came up in very good condition with little or no pitting to the legs.
More grinder and dremel action with the steerer as thankfully, the steerer was just about 4mm too long rather than the hair tearing out too small.
The ride was transformed. The original Columbus forks are around 10mm longer than the Tange and gave the frame a bit of an odd 'feel' over what I've been used and like. The shorter Tange, slightly altered geometry and that over long stem suddenly worked. It now feels like a super fast XC racer from the early 1990's.
The drivetrain is mostly XT so the DX mechs, shifters and levers will make way for more. There is also a NOS Tange Prestige handle bar on its way over from Germany. Just to make the front end complete.
I hope you like it, feel free to hurl the feces if you think I've ruined it!