A Question Regarding Identification Of S-22

First, this is a fabulous forum. I've read often but never posted before. My question is how does one identify an S-22 which is type IIIa when the outer label lines (which must be broken on either top or bottom but not both) are not available top and bottom due to mispositioning of the engraving with respect to the perfs.
Thank you for any comments.

If you can not see the defining characteristics of the type you need to resort to plating the stamp to identify the type. Many people believe that a stamp should only be identified by what you can see. For example, a stamp that plates as a Type III may only be regarded as a Type IIIa if only the break at top is visible. Stamps that can only be identified by plating will, and should, sell for less.

Well put, Sinclair.