Hedge trimmer - gearbox grease

Redmax hedge trimmer. Blades started jamming up, and got them going again. Happened again a few minutes later. It's not the blades jamming, as I have loosened up the bolts and nuts along the blade.

Seems it's in the gearbox. Took it apart, and got them moving again, but definitely not smoothly.

The grease looks pretty cruddy. Is there a certain grease to use, and can I fill it up around everything and put the cover back on??? Or more sparingly??

Thanks....

Hedge trimmer - gearbox grease