Hi Steve, I hava Gemini 23TB and my tank and pump are in a compartment under the bed. The “lid” was screwed shut from an outside storage compartment and the rest was nailed shut with finishing nails! I guess they assume you’ll never need to look in there! After removing screws, I ended up prying the lid up and trimming off the finishing nails. Since my bed is on top of the compartment, I’m pretty sure the lid isn’t going anywhere so I didn’t secure it to the frame when done. My reason for getting into mine was low pressure from my pump. You can search my name for the thread with the details of that adventure!
Hope that helps!