On a BUNN it is necessary to place the carafe under the funnel BEFORE you shut the lid because the brewing will commence immediately after the lid is closed. This is normal. The minimum amount of water to add in order to trigger the dispensing process is 4 cups (on the carafe). The unit brews quickly and does not have programming features because it is not designed to be prepped in advance as you would with a programmable drip machine, say, the night before. This is because the water your BUNN is dispensing is already heated and waiting in the tank providing you leave the unit on and plugged in around the clock as the instructions state. The fresh water you are pouring in is what forces an equal amount of previously heated water into the funnel when you shut the lid. Consequently, you do not need to add fresh water in advance to let it heat. Adding water without replacing the decanter under the funnel and closing the lid may, in fact, overflow the tank. For additional support, contact BUNN:
https://www.bunnomatic.com/retail/service/contact.html

I work for BUNN. Has your issue been resolved? The rocker arm is inside the pour in bowl (where you pour in the water for brewing). To get to it you have to take off the entire top lid (not just the spin lid above the pouring area). That can be removed by lifting it up and then you simply snap it back on when you are finished. Hope this helps.