Mokita Super Pump Ain't Pumpin'

[SpicyRiceTea]

As the title suggests, I got this second hand from my friend who told me the machine didn't work.
We turned it on, and realized that no water was being drawn from the reservoir. I could hear the machine making a brrrr sound, but my friend commented that it wasn't its normal sound.
Though it's very likely that I might end up seeing a professional to get it sorted out, I wanted to see if I couldn't fix it myself.
Right now my biggest challenge is unscrewing the pump, I know this sounds super basic, but I don't think I have the right tools, nor am I sure that I'm even unscrewing the right thing (see the first picture)
Any advice of what tools to get, and what to exactly do would be gold right now. I'm in social isolation, so I got some time hahahaha
Cheers

[IFixJura]

Remove the brass nut holding the transparent tubing to the brass elbow. Turn it on again and see if there is any water pumping out from the elbow. If yes, use your finger to block the elbow hole to create some pressure. If the pump can overcome the pressure and still pump water out, the pump is good. The problem is blockage somewhere downstream in the system. Check one by one flowing that transparent tubing until you find the blockage. Good luck!