I had not seen this publicized, but the Tolkien Society website has a Members Area, for members of the Society, and if you login to that

In this area you can download electronic copies of Amon Hen and Mallorn

Amon Hen (218 - 245)
Mallorn (45-54)

The site states that they aim to get as many issues as possible into here from the archive, but they have to be scanned and that is a time-consuming process.

Have to say, new web site is great, and well worth a visit for anybody who has not visited in a while