My pleasure, ellenbr. Would you know what that number refers to?

The gun was pretty tatty at the time of purchase and left me little choice but to learn how to disassemble a shotgun completely. Despite that, removing the nail/spindle and toplever wasn't exactly difficult, though I did have to study the working of the inner parts.

Would I be right to assume that you have worked on other toplever shotguns and find them easier to dismantle compared to the Brno ZP series?

One thing I did find very difficult was removing the faux hinge pin cover as I had to rehinge the gun. Made a new lock (?) as well as part of the original was broken though it did not affect the working of the gun.