[Elecraft] How do you go back to older firmware release.

[Mike Weir]

I have seen it before on the reflector but can't find it and that is how to go back to a previous firmware release? I currently have 4.51 and want to go back to the one before this until the CW decode is fine tuned. I have the latest P3 firmware downloaded and working but the decode is not a sharp as it was in the previous firmware. It's ok in 4.51 but not close to that of the other firmware. 
Mike
VE3WDM