It's not really difficult is it?
If the SEP rating is valid and the other revalidation by experience requirement are met then you just need to do a one hour instructional flight prior to the SEP rating expiring and get an examiner to sign the revolution page.
If the SEP rating has expired then it is an LPC.
As examiners we can't sign a rating that has expired even if the requirements have been met as it would be illegal. Therefore it's wise to ensure you get everything sorted on the THREE month window allowed....