Very small throttle PWM value range?

Throttle seems to only be on full blast or off. If I really try and fine tune the range it only seems to be something like 1710 - 1780 (0% - 100% throttle), which kind of works, but doesn’t seem ideal.
Everything’s packed in tight so I’d like to avoid removing everything to get at the ESC to calibrate it, but I think that’s what the issue is.

Is there anything else it could be?