Ha that depends upon motor skills. Thanks for your interest: do you need to take off the whole unit, or can you somehow prise of the glass and attack it like that? I always think that once you start delving into these electronic/computer gizmos that you might fix the tacho only to find something else is now awry when you've manhandled everything back into place.
Yes remove clocks from bike, separate case and it's all there. It's really not that difficult if you a. take photos as you go to aid reassembly & b. take it easy.