I'm having a similar problem: NS4G WiMAX stopped working on Feb 9th.
- still in same area of strong coverage, also tried other parts of town where it always worked.
- started with turning phone off and pulling battery.
- reprogrammed phone from within terminal mode(re-entering phone# and MSL code), phone then restarts
- deactivated, then reactivated phone meid from my Sprint account.
- note that I also have a Sprint Overdrive Pro and Clear Spot 4G and WiMAX stills works great on both of those.
- Finally, as last resort, did a hard reset on th phone.
- during entire process, WiMAX connection status in settings shows: Connecting, Initializing, and Disconnected in quick succession.
Still no WiMAX functionality. After telling
Sprint tech support all of this, they suggested it is most likely my hardware that has failed, as I had feared.
Hope that gives you some ideas.
- TouchPad with webOS, Pre 2, Nexus S 4G