That's pretty much what we've concluded too. The problem with it being in the UK is that obtaining a replacement is a lengthy and expensive business, due to HWH locking their business into one European supplier (in some eastern country, I think Hungary?). They in turn do not hold stock and have to order from HWH in the US, so it takes weeks for it to arrive and is marked up by around 150%. I got around this by getting the equalizer valve easily here in the States and shipping it to the UK myself (something HWH would not approve of).
I called a second hydraulic repair specialist in our home town this morning, who immediately understood the issue and said, "Yep, we can fix it". This confirms Mavarick's and Tom's helpful input, for which obviously I'm grateful.
The RV guy is therefore dropping off the ram tomorrow to the firm, who will give him a costing & timescale there & then. I didn't realise he'd removed both rams off the RV. He's had them working and connected with the rams facing outwards to see exactly what is happening (i.e. turned 180 degrees with cylinders supported on axle stands). This feels like progress, finally.
Dougie.