Bollocks.
I used spring compressors and the spring plate was well free of the spring. Put the top mount on and screwed on the slotted nut. All the way. Cleaned the treads as well, but still a little bit of a wobble.
It would'nt tighten any more and the notches were flush with the mount, so I could'nt tighten it further
Took it for a spin, all is well. Slight metalic vibration noise, but I guess thats from something in the engine bay like the heat shield.