Hey Witt. Getting the cluster out is not that difficult (I managed it!)... I'll throw out some guidance but recommend you search here and the tech manual for particulars. First things first, you want to unhook the battery, and remove the steering wheel (gives you a bit more room and you will need it). Then remove the driver's side under dash panel and unscrew the wire harness and carefully push it out of the way. Then its time to remove tachometer. Much of this is by feel and its very tight but try and shine light from underneath as you are wedged on your back looking up. If lucky you can see the back of the tach. Find the tach cable and loosen it. Then loosen the finger nut on the bracket of the tach. The ground wire will be on this screw. Remember that for the reassembly. In fact remember all this for reassembly. Next comes the tach light bulb housing. One light housing pulls out with bracket in place, the other after the bracket is off. Then the bracket should come out. Next push the tach from behind gently, it will start to pop out the dash -- grab it. Pat yourself on the back.
Now, you can reach inside the tach hole and start on the center cluster. There is a threaded oil line? that you must carefully unscrew. Having two wrenches helps - one to hold the nut on the gauge steady and one to turn off the fitting. You will also see the temp sensor cable back there. Since your capillary is shot you don't have to be ultra careful around it but its good practice for when you put new one back in. Then find the finger nuts for the cluster bracket and unscrew them. Again pay attention to the ground wires that are attached. You do not need to unattach the temp wire -- except at the block (or in your case it is already loose). You also need to unhook the large wire cable connector down by the left footwell. Once everything is unhooked from back, the center unit will also come out the front with the capillary tube and the wiring cable like a tail. Carefully pull it all out. Pay attention to the grommet it came through at the firewall. Go have a beer.
PS if you send it out to be repaired, they will likely have new chrome bezels available for the tach. Not expensive -- the temp gauge ones, however, very expensive. You also want to get new rubber gaskets for the instruments -- contact Dave Gallon.