On 20/11/2017 18:24, Harry Bloomfield wrote:
Brian Gaff was thinking very hard :
Probably welded it up a bit.
*I'd not actually suggest it was never tightened. I've seen these
things just get loose due to collapse of the wire itself into a flat
squashed lump.

Especially true, where the wire end has been tinned for ease of assembly.

Interesting. The wire ends were indeed tinned. I replaced the plug and
ensured all was tight.

Mike