The latch has to come out anyway and I plan to supply working latches. Not everybody can strip and replace the switchgear and that includes some that think that they can so it is better for me to send a known good latch.
Whether that is by refundable deposit on receipt of your old core or just send one out on the same day I receive it, I have not yet decided.
The reason for making a jig is so that the returned latch can be fully tested so that there is absolutely no doubt that it can be fitted and forgotten.