After an "episode" using the multimeter on my car I blew a fuse. Anyway, I didnt notice the blown fuse until I was ready to roast some beans. So under the house on dirt after a few beers i thought it was a good idea to take apart the multimeter.......mmmm.
I was in a rush and after running some wire across the fuse (I know...) I began to quickly screw it back together a bit impatiently as I was already behind schedule. I put one of the screws into a whole in the circuit board and screwed but it did not really tighten, as it should. That was because I had screwed it into an adjustable pot and destroyed it! After that, the multimeter went a bit crazy, reading out a bizarre negative temperature, something like negative 57c and would only "climb" in a negative direction.

Short version is I got a 20k pot (98c) from Jaycar and a new fuse (40c) , I replaced the small fuse (240v, 500ma) and soldered the pot in. The following bit is what I wanted to share (for those who dont think their temp is remotely right or if they blow a fuse like me), I had to calibrate the temp by simply turning the pot I had replaced, I boiled some water and set the multimeter to read around 99c. Shoved the probe under my tongue later and got a reading of 36.6 after 1 minute so close enough for me.
You need to undo 5 screws on the back of the unit before you get to circuit board (one of which is the battery cover - mine ended up in the dirt somewhere)*Once your in my my main tip is to only undo four screws from the circuit board when separating it from the face of the unit. 2 screws are located at the bottom corners and the other 2 around 4cm from the top corners. * When separating the board from the face you have to gently pull it apart as the dial knob on the front face if firmly pressed in a rotary switch. I was stupid enough to undo more than just the 4 screws and the little internal parts of the rotary switch fell out (that is another story).
Here are some pics:
The new pot in place, the dead original one sitting next to it.


and the hole (top right) that i should never have put screw through!



I am pasting this as FYI and not trying to encourage people to rip apart their functional Multimeters.