I'm sure many in the industry are aware that Chabad are makpid that the batim shel rosh should be prudos legamri (no glue between the rosh batim). This is based primarily on the Shulchan Oruch Harav.
I was discussing this issue with another sofer in NY over shabbos and we were discussing that while obviously when selling new tefillin to Chabad we should ensure that the batim are prudos (and check them as such), what would be the accepted practise when it comes to used tefillin that are brought in for checking? Is the checker chayyev to start sticking knives or other instruments between the batim, potentially damaging the persons tefillin, in order to check the prudos? By doing this is he going over and above what is required when someone brings him tefillin for checking?
We were interested in Reb Moshe's opinion on this matter.