DO35 Hitch

Brenton.
That 0.5 mm is not much clearance for the hitch to gather momentum to make noise. If it is can you fit a fibre washer to hold the movement.
However, have you checked the clearance and possible "Ovality" of the drop on section and the hitch pin and the radiall clearance involved. I would think the fore/aft slog will wear the pin and ring section.

I don't know the answer to your question, but recommend you ask the manufacturer. I had a Mk 1 DO35, which due to a silly mistake on my part developed a noticeable clearance between the centre section & the yoke in which it pivots. I measured it & called the manufacturer & straight up they told me it was no longer safe & suitable only for the bin. I now have a Mk 3 DO35 (which is a significant improvement).