The problem is, that these samples are certainly overprocessed and overdehydrated. This cannot really be repaired. The only thing to make cutting easier is to rehydrate the trimmed surface of the block. Let the block swim for a few minutes onto a waterbath. Watch out, if you do this too long, the tissue will swell out of the block.
Then cool the block again. while cutting breath onto the surface for a better humidity, take sharp knifes, tighten everything very fast on the microtome.