Treating old velvet with possible dry rot

I have a vintage Paquin that has a great deal of damage. The velvet is crunchy to the touch. The jacket is so damaged it is unlikely I can save it but the dress only has a few crunchy spots. I am determined to save the dress. What is the best method of cleaning old velvet and treating dry rot? I would rather not take it to a dry cleaner, I am afraid they might just make it worse by throwing it into a massive tumble washer. Would hand washing washing it in a mild detergent and a bit of mild fabric softener help?