When new, the temperature gauge was at about 9 o'clock and the heat was fine.
Now, in winter, the gauge peaks at about 8 o'clock and the heat is poor. Putting cardboard in front of the radiator doesn't help.
In summer, the gauge goes to about 10 o'clock, sometimes even higher. The fan does go on.
Coolant was changed last year. No loss of coolant. Water pump has about 60K on it. Radiator, hoses and thermostat are original.
I can think of many possibilities for overheating or under-heating, but what could cause both?