Peter

I have just been through the process of moving my upper spreader mount as I had a lot of binding of the diamonds on my side stay wires. I measured a mast at my club and the spreader upper mount was 300mm below the hounds. This is from the eye of the hounds to the upper hole of the spreader wire retainer (Ronstan style). Now when I did mine to this dimension I still have a little binding downwind as my system compared to the one I measured is slightly different styles... a bummer as I thought I had cured the problem for good. I initially had binding so bad that upwind the spanner would not rotate past the rear of the centre case... not good. So anyway I would look at spacing the top of the spreader retainers around 350mm from the eye of the hounds. I will be replacing my mast next season and will re do at 350mm...

Hope this helps..