Hi Geoff,
your prob sounds like it could be either a cable issue or the shifter tower...not sure about the Quaife...to be honest I hear that most dealers hate stripping an MTX ( I have a Forrd dealer in Il who sends the transmissions to me for repair!)...so I doubt they will fit a quaife but you can try...TH

V6 MTX
'Don't p**s up my back then tell me it's raining!!!"
'Its only nuts & bolts!'
'If I build it,fix it,upgrade it or modify it...MAYBE they will come....!
Haines Motor Sports Inc,
Dealer for 'Quaife America' & 'Autotech Sport Tuning'
SOLE USA Dealer for the American Axle 'AUSSIE BAR'...
Get a Turbo for you Zetec from HMS Inc...by 'The Demon' ...www.DemonDynamics.co.uk
..don't talk about it DO IT !!!