Can anyone tell me how to replace the washer in the taps/shower selector handle of a traditional brass combined tap and shower bath fitting. The unit comprises two front facing horizontal hot and cold taps with a central quadrant lever that selects tap or shower flow from the shower pipe which exits from the top of the unit. The washer in the quadrant lever has perished; I have been able to undo and extract the quadrant lever's barrel and removed the remains of the washer. However, I cannot see how to fit a replacement washer without access from above - and this is not possible unless, somehow, I can remove the joint (if there is one) where the shower pipe emanates from the top of the unit.
Grateful for any advice - other than buying a whole new unit!
Take a photo of your tap setup and go to a local plumbing/hardware store and show them at the counter. Tell them you want replacement washers and if you happen to know, the model type or number of the taps.