Hello
DrHenkMaybe a member has better info than I have.
Finding NOS link belts is unlikely now.
When I first looked at the Rover HD 25 the most obvious oddity was the
link belt. I had never seen one before on a rotary mower, but it made
sense for the application. It was old technology by the 1960s.
Acquiring a link belt for this mower should not be a great problem.
https://www.powergrip.com.au/PG_Transmission_BTR.htmA local power-train supplier (like a bearing seller) should
be able to identify the pulley profile for a top-ling belt.
Hope this helps.
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Jack