Aye Dave,
Welcome to the forum and thank you for the head scratcher!😉
Hen's teeth and rocking horse poo appear to come to mind and the prices may prove prohibitive, but here goes.
Manifold_motorcycle_parts This company is unknown to me, but appears to trade through eBay and has a large number of units/parts in stock for the DR125 models. I suggest a direct call first and see how it goes from there.
I have found Betor shocks to be of good quality and gòod value, so here is their website:
Betor_shocks Again contact direct for details as I am not sure if they cover the DR125 SEY model specifically. Price appears to be €200 + VAT + P&P
Finally, Hagon, like Betor list a unit for the DR125, but not specifically the SEY model. Their website is:
Hagon_shocks Contact direct for details and be aware of £299 price!
Hope this helps. I have some other contacts, but cannot get them on this borrowed tablet I have whilst crocked, but will try to get vertical and sort something out.
My regards, Bill