Facing the 0000/max scale issue, after some reading I decided to look into our TM5. I found somehow strange that some people fixed it “cleaning contacts” or just “disassembbling and re-assembling”. I’ve worked before with load cells, and they are “solid” devices, with soldered and glued connections in the cell end (no contacts to clean there).
So I looked at the mainboard end of the load cells wires, at the right back side of the board. While checking the connectors, I noticed that the wires from the three load cells (three groups of four wires each) run quite near the board components, even touching the board, and had ferrite beads around them to reduce electronic noise.
Load cells produce quite small voltage signals, so they are very sensitive to noise from board components. So I just pushed wires and beads some milimeters away from the board, checking they kept there after reassembling.
Now the scale works fine (I’m too lazy for further testing, maybe connecting an oscilloscope probe to load cells output while moving cables would confirm or discard this theory).
Hope this helps.