With the symptoms you've reported, I suspect there is either a clog in/around the grinder, or that the beans are simply unable to make their way into the grinder from the hopper. At the most basic level, I'd suggest removing all of the beans from the hopper, removing the plastic finger guard "dome" from the center (it's held in by a single philips head screw), and then vacuuming out the center (easily done using a small hand attachment for a vacuum, or simply a bare nozzle pressed flush against the center). This would help clear out anything that might have accumulated there. From there, you can try wiping down the hopper in a two-step pass to remove excess oils and spread the remaining around evenly--use a damp cloth (not soaking wet) and wipe across the entire hopper, then dry it with a dry cloth/towel.
For re-assembly, you don't even necessarily need to reinstall the plastic dome, as it may be catching on the beans you're using and holding them back, depending on how sticky or oily they are. If you choose to leave it out, place it in a plastic sandwich bag and try to avoid poking fingers into the running grinder for largely obvious reasons.
You can try putting beans into the hopper again once everything is completely dry.. Repair is your next step if the problem persists.