Often companies get someone to train their team when they adopt Scrum, but a few months or years later, new staff have joined, others have left, and very few people remain who have received formal Scrum training. As a result companies suffer because people understand the mechanics of Scrum but not the principles and values behind it. This prevents them from effectively inspecting and adapting.
It’s not always feasible to get an external trainer to train your teams on an ongoing basis. I have a solution! Train them yourself :) Before you tell me you can’t, take a look at this book: Growing Agile: A Coach’s Guide to Training Scrum. It contains everything you need to run a Scrum training session from 1 hour to 2 days. Workbooks, slides, simulation, the works!