IIRC the two emergency ways of getting the NLG down on the C130 were via the aux pump and a changeover valve on the forward port side of the cargo bay and the 'freefall' method via a lever under the co pilot's feet. If using the former method then a few pumps with the handle would check whether the system maintained pressure before using the aux hydraulic pump full pressure.
There was a small mechanical indicator on the NLG itself but to check it meant taking off the always dirty inspection window. I am would be surprised if the C17 did not have a similar system.