Interesting find and tip - for the last 2 years I kept hearing a rattle from my trailer when towing. Spent quite a few hours in the garage checking everything but found nothing loose.
Then I noticed the other week my brother-in-law had a rubber strap holding his jockey wheel tight against the rail when he towed... then the light suddenly went on! So did the same to mine and the rattle miraculously disappeared.
You can see in the pic below the jockey wheel without the rubber strap - give yours a shake - I bet it rattles too!
Never noticed in the garage as it had the weight of the boat on it... Doh..!!
