Avanti Single tap kegerator owners, I need your thoughts

I'm visiting my dad and he's had an Avanti single tap tower kegerator that has been a foamer ever since he's owned it. While I'm down here I'm looking to fix this for him. It's set up for commercial kegs so the diameter of the beer hose is probably 5/8" and it about 5 or 6' in length.

The temperature is 41 degrees when taking the temp of a beer pulled. He has his gas pressure at 6psi, which I definitely know is too low.

My thought is that he's getting foam because his gas pressure is too low and co2 is coming out of suspension and filling in the tube.

He typically gets sixtals of fosters etc. Should his gas be set at 12lb psi based on the beer hose size? How can i help him?

While I dont have that make/model, I had similar experiences with my kegerator when I first got it...Start by checking the temps at various places inside the kegerator. In my case I had a good 5 - 10 degree difference between the bottom of the kegerator and the top. I placed a small computer fan inside to circulate the air better. Once the temps evened out and stabilized, it worked soo much better. You can also consider increasing the length of the beer line but try the fan first.

i have the same issue with mine, i tried doubling the length of hose but it didn't change anything, i do have a 5 degree difference from the top to the bottom of the keg like unabonger said. hopefully a fan helps me out because adding length to the line did nothing.