Beer isn’t coming out of the tap even though the CO₂ tank is full. What should I check?

I had almost the same thing at my restaurant. I checked the tank, coupler, and faucet first, and we even swapped the regulator. It still wasn’t right, so I stopped buying random parts and had the line checked. If you don’t hear any gas at the coupler, I’d start around the regulator and coupler. I wouldn’t keep forcing it.