Optimus 8R & others, do all Optimus stoves have a 5mm diameter needle shaft where the packing goes? I don't really know squat about the stoves, but I punched out some 8mm OD 5mm ID compressible graphite packing rings and are curious about what else they might fit. So far I have my 8R running them, and a buddies 111B. Anyone know how universal the 5mm diameter needle was on the Optimus stoves? Thanks for your time.