Thanks everyone, sorry for the delay, was kiteless until yesterday.
"Seemingly" broken cleanly off. Did you find the broken missing piece? If no,,,
My guess is the glue broke loose and that piece slid down into the tube, you need to break the other one loose and pull it out pliers work ok, I use a long metal rod to push those pieces out, then reglue them back in.
Thanks Hyza, you were right about this, the problem occurred just after inserting the spars into the central LE and tightening the bungees. After it 'broke' I pulled all the spars out of the LE fabric and there were no broken missing pieces, it just looked like the left LE had snapped cleanly off the ferrule. I couldn't understand how it happened.
I now have the kite back in my hand and can indeed confirm the affected ferrule had simply slid into the central LE. I didn't realise the central LE was just a regular rod and that the ferrules were separate pieces and simply glued in place.
Using your advice I've since managed to get the other ferrule off with pliers, and then used the pliers to straighten a strong wire coat hanger to poke the other problematic ferrule back out, many thanks for that! Seems the standard glue holding the ferrules in situ isn't very strong. Will use superglue to reglue them.
Will also still be grabbing a lighter frame and thanks to everyone's advice I will likely forgo the Diamonds for now and get a set of Black Race Rods to compliment the 3-wraps for low wind, and educate myself further in those conditions. I'm not content with waiting for slighlty windier days!
Just for interest, I weighed my 3-wrap frame - 101grams for the full set (5 rods + 2 ferrules) in total. That compares with other people's weights of 75g for the set of Race Rods, and 50grams for a set of Diamonds.
Back to the 3-wraps, the four single outer rods (not the rod used for the central LE with ferrules) individually weighed in at 16g, 17g, 17g and 20g. A moderate discrepancy between the 16-17gram rods and the 20g one, which was odd, especially as the 20g rod was one of the ones on the side. To rule out user error in weighing, I re-calibrated the scale and weighed the rods again and the same figures held.
The central LE rod (with 2 ferrules) weighed 30g. The ferrules weigh 5grams each, the central LE rod itself (without ferrules) was also 20g.
Knowing this, I calculated the Left to Right distribution ratio of weight of my previous frame layout as being 48:52 grams (L:R) of the kite, meaning the right side weighed 4grams more than the left (about a 7-8% difference in the frame). The difference would become negligable when you factor in the weight of the rest of the kite, and also for an amateur pilot's technique, but I may still use this info to redistribute the rods so they balance out a touch better, such as placing the 20g rods either side of the kite and allocating one of the other rods to be the new central LE and attach the ferrules to it.