Did you put an Oring in the groove on the new purge valve assembly? There is one on the old valve in your pic, but not on the new valve…
When the governor reaches set pressure, it unloads the compressor and sends system air pressure down to that little plastic line attached to the bottom of the dryer, That air opens the purge valve and vents the system.
When is it leaking from the purge valve port? When filling, or when unloaded?
If it is leaking when unloaded, your leak may be the check valve at the top of the dryer, leaking air back into the dryer and out the open purge valve…