I drive my 240 (SuperPolar B200F 1992) from 1996 as my daily driver, well cared for, and everything (now +650k km on the ODO).
I bought her when she was 4 years old with 110k km on the ODO.

Now I suspect (after 27 years, so no complaint) that the temp comp. board has failed since it's stable over 10 o'clock, so I got ready to do the infamous bypass. Of course, I have done all the needed maintenance in the cooling sector.

The temperature measured at the thermostat cover is around 88°C (the thermostat is 92°C) so there is no need to worry, but I can't stand to see the hand well over the middle.
But once I opened the instrument box I found no compensation board at all, and no bypass was done. I can exclude that something could have been done by the first owner (a failure in the first 4 years, no way!).
So, what is this mystery?
Until 3-4 months ago the hand was sitting in the middle with minor movements up.
My curiosity is how the meter can correctly work without the board and without the bypass.
Your help in solving this case is very much appreciated! Thanks!