From: Rabbi Moshe Sofer
To: Rabbi Kashman
The Chasam Sofer rejects two proposed leniencies for a house with over forty sealed mezuzos owned by three partners: partners are not classified as 'the public' (rabim) and thus must check their mezuzos on the individual schedule of twice in seven years, not once per Jubilee. Furthermore, while inspection does not require scribal expertise, the mezuzah cases must be physically opened and each letter examined for deterioration due to moisture.
Source: Shu"t Chasam Sofer YD §283