Hi all I bought a Danby Millenium model number

KC445BL kegerator used off of ebay. I'm having a problem getting my beer down to 38-40 degrees. Right now its 50degrees and the thermostat wont go any higher. I have a glass of water with a fishtank thermometer in it and its been reading 50 for two days. I was wondering if anyone has this model and if so how cold is your beer.The thermostat has a round knob with a groove in the middle and not the didgital one.I can turn the nob the hole way around....something wrong or is there a way to fix? I drink 1/4 kegs of bud..nothing else. Pressure is set at 12 and the first pour is always half foam which I contribute to it not being cold enough and it also needs cleaned. Help please...Im new to this but so glad I found this site. Thanx guys!