Thanks for the reply. That's very helpful.

1) What's stops the traveller moving side to side if the cleat is mounted to the traveller? I thought the cleat would have to be fixed to something (the beam I thought) for it to limit travel?

2) I appreciate this detail. I'll have a go at setting it up like this.

3) Yep, need to find a similar system and replace it all.

Cheers,
Matt