thanks guys, seems that I was heading down the wrong path and now we have a partly busted instrument panel - i knocked the needle on the temp gauge and now it doesn't work at all... 
re: the speedo sensor, does anyone have a piccy where I can find it?
Also re the 13mm nuts on the steering column, are they obvious to locate?
Cheers!

re: the speedo sensor, does anyone have a piccy where I can find it?
Also re the 13mm nuts on the steering column, are they obvious to locate?
Cheers!