Maureen,
The simplest way that I have found to cut these very thick brain sections is to face the block, remove it from the microtome, float it in the 45-47C flotation bath for about 1 min, then place it back in the microtome, and cut your sections, float them out on the water bath, and pick them up in the usual manner.  As the block cools down the sectioning will become more difficult, so re warm the block and then continue.
Kerry Beebe
bbracing@silk.net