Hitch upgrade for cargo trailer

[Zanda]

I have a cheap cargo trailer with a spring hitch at the left side of the bicycle's rear axle. It is the usual design of a steel spring connecting a short piece of tube to the trailer's draw bar. I have found the trailer handles poorly when heavily loaded and suspect the hitch is to blame. When I accelerate, the trailer drags, then stops dragging, then drags, then stops dragging. Perhaps three or four times.

Seeking to upgrade the hitch, ideally to eliminate the spring. I like the simplicity of the Carry Freedom Y-Frame trailer's elastomer hitch. SJS sell these as spares for £55 and I imagine they can be retrofitted to other trailers. Anyone retrofitted an elastomer hitch of this type, as an upgrade?

Any other options for an upgrade to the hitch?

[Tilley]

Weber make a more substancial trailer hitch but it isn't cheap.

[simonineaston]

I had a cheap trailer, into which I popped one of them red elastomer lollypop jobbies and can report nothing it all - it fitted & just worked. I bought it direct off of the makers, Carry Freedom.

[gaz]

I tow a Raleigh Mule via a Burley elastomer hitch, like this. Burley did (do?) elastomers for square tubes or round tubes, look for the right one. Burley also say the elastomers are only for use with Burley trailers.

Copies of the official Burley steel hitch to attach to the axle are widely available and cheaper than the branded version.