I have a bicycle trailer (Hamax Outback One). Recently I inspected the hitch as I was connecting the tow bar to the bicycle. The steel spring was getting rusty, but I do not think it's a big deal. However, inside the spring there was a black cylindrical rod which I assume is made of some sort of elastomer. That part seemed to have broken into two pieces.
I started looking for a replacement or a fix for that. There are a lot of similar complete replacement hitches sold online. However, the dimensions of the parts, especially of the coupler that stays on the bike's dropout, are slightly different, meaning I'd have to replace the whole hitch and buy new couplers for multiple bikes. Alternatively, a complete new tow bar for Hamax trailers can be found, but that is more expensive and really not something that I'd need.
On the picture below, the transparent elastomer part is sticking up out from the steel spring.
The question is: how important is that for safety that the elastomer is in one piece? I assume its role is damping when the spring gets compressed at braking.
Additional question is that if anyone has done that I plan to do, that is, to buy a no-name hitch and reuse its new elastomer alone. Or maybe there are other DIY sources of the elastomer part?