Ignition Or Carb Problem???

Trophy 900 1993, 110,00 miles on the clock. FIM rally in Lithuania, low on fuel so fill up in a remote s./station
soon after a bad misfire at quarter to three quarter throttle, obviously dodgy fuel?
Carbs off clean out float bowls and blow through main jets,- no improvement? Spark plugs then ! cleaned, gapped, coil leads checked, plug leads checked reassembled, no improvement ???
Got to get home so be brutal, ride through the misfire to 60/70 mph a bit lumpy but ride-able, only around 1300 miles!
Once home strip it all down again ( can do it blindfold by now) carb complete strip down and find one needle worn through and the other two almost through. Why did I not see that in Vilnius, well when you lift the slides the needle is down and if you turn the carbs upside down the needle doesn't move, only when the tops and diaphragm are removed does the broken needle fall out.
New needles and clips, a lot better now.
Something to bear in mind if you have a high mileage bike.