The bag storage place in T4 is open (bottom of escaltors from the AirTrain).. 2 people in the queue and its taken 20 mind to do the first person with one case so far. Must be ex-TSA working there!

Fill in a form with name, address, phone, email, passport, pickup date and time etc.
Shiw passport andvonward bp.
Go into n office and get bag checked, scanned and sealed.
Pay $16.xx (small bag size $15 + tax).
Get a receipt which you show with your passport on collectuon.

Be aware there are Airtrain works at present, so tiimings are slower and there's a bus service to T1 and 2.