Kevin McCormack refurbished some old LOM leather cases for me. When they got back from him and I saw the change in the leather I was amazed. I contacted him and asked what he used to do it, he told me he first used a product which I cannot remember the name of, as a cleaner. Then he conditioned it with Blackrock Leather-N-Rich. I bought the Leather-N-Rich and use it regularly to rejuvenate leather and keep it healthy. Wish I could remember the name of the product he recommended for the initial cleaning step.

I realize this product has already been mentioned but thought I'd add my endorsement of it, FWIW.

https://www.blackrock-leather.com