Make sure you are packing the plates correctly particularly with respect to any dished plates marked with a centre punched type dot. These need to go in facing correctly and in correct order do you have a Haynes manual or similar?
yes, on this there's only one dished plate and its in corectly, just put it back together and i've popped the slave seal. numpty me! hopefully it will be fine once i've done that. just off to pick up a seal.