Getting to the tachometer is very difficult and requires significant dismantling of the dash. You need to remove the trim, speedo and centre gauges to get to the tacho, it's a big job. Removing the steering wheel and removing the front seat will help too with access. You will also need a small child as you need tiny nimble fingers to remove some of the various nuts etc.
If you really want to attempt this think about replacing the dash bulbs and overhauling the heater controls at the same time. That's what I did and took me about three weeks! on and off.
That's the bad news. The good news if you have an auto, if i recall correctly and am not getting the taco cable mixed up with the speedo cable, you can detach the cable at the transmission end which I what i did. You can then remove the inner cable lubricate it an put it back. It takes about an hour but you do need the right sizes hexagonal socket. Can't remember the size but this has been covered on the forum before. Much much easier.
Good luck,
Peter
