My cunning plan to resolve our sticky shower valve having come to naught, I emailed Bristan asking for advice.
I received an email asking when I'd purchased the shower. I replied February 2019. They replied saying that they'd pop a replacement valve in the post FOC, which should be with me in a couple of days. There are comprehensive fitting instructions in a attached PDF, they also offered to send one of their service engineers to do the work, but they would need to charge £79 if I chose that option.
That's exemplary service, I'd mentally pencilled in the cost of replacing the shower, so that means I have a bit of extra money to spend on fripperies vital upgrades to the bikes.😎