I thought of two other places, in the Tampa area, not internet shops but might have "stuff." One is Don's Marine Salvage in Clearwater. But if it's there, you'd probably have to send somebody to find it. Customer service is not on Don's menu. What used to be a good source is T.A.Mahoney. They had an old store with enough dust to bury most of the smaller items. But they knew Which Item was under Which Dust. That was a generation, maybe two, ago. Now they have a big sportfishing boutique and maybe got rid of a lot of the odd stuff. Now that I think more about this, three other possibilities all in FL though:
Surplus Unlimited on Speedway Blvd in Daytona
Sailor's Exchange in St. Augustine
Pier 17 in Jacksonville - the elderly owners passed away and the place is now owned/run by Sailor's Exchange. Those people, at either location by either name, ARE helpful, and they'd likely understand what you're looking for.
If you haven't try to find a number for Aqua Signal and see if you reach a "good old soul" who knows a little history. My wife ended up talking to somebody at Whirlpool about the broken hinges on our dishwasher. Conversation was "Hmm, we changed those, then we discontinued them but you know I thought I saw a pair... Yes... Got them in my hand... Not in the computer anymore so I can't sell them. What's your address? I'll just mail them to you."