I have some experience with tesseract. In my case doing some morphology to merge disjoint parts of letters helped (We used bank tickets printed with matrix printers).

In addition, and I think this is the most important. We trained for the correct typography, and that boosted from 50% to 90% in the performance.

Thank you juan cardelino

My pleasure I hope it helps. The training process is tiresome, but works. Be sure to have good samples of every letter for each typography present in your documents.