Do you mean remove the internals or take the whole valve out of the wall, either way give National shower spares a call they are experts on all things Mira.
0845 126 4141 or www.showerspares.com
Gary
December 2011
Automatic Answer
While you wait for answers, we may have found some information which could help you.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix plumbing.