Roberts RT1 which has been dropped

[Refugee]

Have you checked with a magnifier to see if both sets of moving vanes are central between the fixed vanes when they are fully closed?
I did a Bush TR82 that had been dropped and the frame of the tuning cap had sprung just enough to very slightly bend the vanes at the end furthest from the control.
The solder had to be heated in order to align the vanes again.
http://www.forum.radios-tv.co.uk/viewtopic.php?f=3&t=6577&p=67891&hilit=TR82#p67604