Thanks for the continued interest, as I too would like to learn from these projects...
This is another of the DMMs I got Sunday,,, seems its still a currently available model... but other than a simple instruction manual, no other paper work is available... will post interior pics after camera battery recharges...
It reads a 9V battery at about 6+ VDC,, approx the same % low reading on ACV, DCV and R modes...
So far, I've replaced with fresh battery, and swapped out RT1 which reads 1200R with lower value resistors,,,, that allowed the readings to climb incrementally, but would go past teh known reading and just run away (I put the original. thermistor back in).. my thinking here is it needs the limiting factor of a thermistor,,, but I could be wrong...
More info to follow...