On YACF, every day's a school day.
I can't remove the black plastic seal on the right hand side of the hub. Does anyone know which size of spanner I need? I doubt have one big enough. Today I took it to Homebase but none of their spanners were big enough. Needs to be a ring spanner.
In many cases you need a full octagon spanner to unscrew the internal from a shimano dynohub. Standard spanners and sockets won't work because they are hexagons, not octagons. Shimano make special spanners for this job. It looks like you could use a headset spanner, but invariably they slip off the fitting and damage it, because they are partial, not full, octagons.
BTW re testing; apols if this is obvious but with most multimeters if you are testing for current, you need to have the leads plugged in a different set of holes in the front vs volts or ohms, etc.
cheers