[Freeswitch-users] Need git help - how to download a specific date version

I need to download a fresh HEAD using git, but I need to be able to specify the rev level or date (preferably). I am trying to solve a build issue that "goes away" on the second make which is why I need a fresh reload each time. A problem was introduced between and 9/26 and I am trying to narrow down the actual date/time it happened. I was not able to find out how to do this on the web. Thanks Mario G