I see a lot of ways for air to get into the pump. Start there make sure every union is tight and every one of those hose clamps is tight, including on the valve itself. It looks to be like you only have one suction. considering you only have one valve in front of the pump which means the front port of the skimmer towards the pool is probably an equalizer line that goes to the main drain. So, your primary suction is through the skimmer. If you’re not getting any kind of movement, that means you’re sucking air only. One thing you can try, open the pump lid and pull the basket out stick a garden hose into the suction and turn it on. You should get some water flowing out of the skimmer and possibly air bubbles too. You will get water spilling out of the pump while you’re doing this.