The 10th returning Ranger will be revealed at some point today. Keep in mind that they're in California so it would be 6:01 PM over there right now due to them being in Pacific Time.
Here are the hints according to FuryDiamond.
1. Original Saban era
2. Not from MMPR
3. Not from Galaxy
4. Not from Zeo (although that was plainly obvious)
5. Not from Turbo
That means the following are current candidates
Space
Christopher Khayman Lee =
Justin Nimmo =
Lightspeed Rescue
Alison MacInnis =
Michael Chaturantabut = Stated he got invited.
Time Force
Kevin Kleinberg =
Michael Copon =
Deborah Estelle Phillips =
Daniel Southworth =