I recall adjusting the pointer on my MK2 SX pods to read 0 mph when stopped, then the Speedo became out :bang:
Chas told me that they are set so as they can't really work below about 5 mph it's just the way analogue Speedos work
put mine back and it's been OK ever since. The original base one used to stick and wouldn't go below about 10mph, without lightly thumping the dash :devil: perhaps yours is the same.