Filament Gear Inoperable

[jdlev]

So what I thought was a clogged extruder has turned out to be something worse. The filament drive gear has zero drive forward or backwards.

...and I just figured it out...but thought I would post how I fixed it to help anyone else having the same issue.
The M2 has a feature that prevents cold extrusion if the v4 isn't up to temp. To turn off this feature to test the drive gear - open up your communication screen with the M2 and send the command M302.

Presto...drive gear works again...so hopefully I can get back to printing now

[willnewton]

I think the default is about 170ºC to prevent cold extrudes. You can adjust that number in the Marlin firmware, or disable via M302. Also, M302 will persist until you reset, so watch out for unintended cold extrusion.

You can also get a "dead" extruder from a MINTEMP error, where the RAMBO does not receive a temp reading from the thermistor because it broken or mis-wired. The default is 5ºC min required.