24v trolling issue bad onboard charger

[Blood357]

Sorry y’all I’m sure trolling issues are nothing new. I was using yellow top optima batteries and my dual pro onboard charger. I believe one side was going bad and had no idea about special AGM chargers. I now bought two blue top opt batteries and see importance of proper charging. Hooked them up same as others were with one jumper across from one positive to the other negative. Rest of wires go through panel. (1996 champ. Checked v at each battery and read about 12v. I was going to check the trolling fuses on the panel but couldn’t get the fuses out. Don’t want to break them. Any thoughts?

[Tx Champ]

Are they fuses or breakers? Pix would help. Some tournament models had fuses, but Elites have breakers.