wrote

After battling for 3 days with the stupid Flymo spammer,
I eventually put the machine upside down in the sun
Then sprayed it liberally with yet more WD40. Then
I chocked the blade with a big chunk of wood, and got
The longest bar-clamp I have (about 1m). After an hour
In the sun I used the clamp as a spanner, and it came
Off without effort.

Why are you mowing in the depths of winter ?

Is your lawn in a greenhouse ?