I tried search, 'cause I know this must've been asked and discussed, but did not come up with anything. I just brought home an early 20th century Leblond 14" lathe; it is belt drive and someone did a pretty nice job of setting up an overhead motor on a supported mount, with the appropriate stepped pulley and a cam to engage/ disengage. The machine still has its leather flat belt. It has sat in unheated storage in Vermont (summers can go to 100, winters can go to -20 or -30F) for at least (that I have found out about) 20 years, and probably quite likely sat somewhere else for some time before that. Thankfully, it was stored without tension on the belt.. The leather belt is intact but has mildew or some other white crusty stuff on parts of it, and appears to have some surface cracking when it is flexed. I assume that some amount of cracking is unavoidable but I don't know how far it can "go" before it's toast. It seems stiff and potentially brittle. Both my frugal streak and my desire to preserve and use something old make me want to save and use the belt if at all possible. What should I use, and what should I avoid, in the way of cleaners/ conditioners and techniques to try to revive and preserve this belt? Feel free to point/ link me to prior threads if you remember them and can find your way back to them. Thanks in advance for the help.