Hello friend, today you are lucky that there are cheap design solutions. I have two options to suggest you, the first is a single piece that you can order from anyone who makes 3D designs that you can print, just give them the measurements or take photos, or bring the speaker. He can do it for you quickly and you could replace the whole thing to leave them all the same, I mean, with the same style. Here you could replicate those of the original by replacing the fabric it has with a grid made of the same plastic as the 3D extruder, you could even put the JBL logo on it and in one corner your mini "SurfRock66" logo, how do you see yourself with that model? ..wouldn't that be cool? Then you can paint them with any spray and in the color you want, even metallic and give it your personal touch. The other is to ask for the same thing but without the grille, just a support that can be mounted on the second piece and that could be embedded or screwed to the first part of the ceiling. You should only glue the fabric inside (not just any will work, I warn you, some fabrics with a lot of cotton or closed mesh end up making the sound shine due to its absorption of waves) and then you stick the logo. It is a little more difficult but close to reality. Look for any 3D printing design workshop and you will surely be able to solve your problem. There are more ways (DIY) but obviously they depend on your manual ability and knowledge, and if you have asked for help it is because you are not sure that it will work out for you.

This setup is very poor. The screws that are in the wood should be through bolts from side to side with grade 8 steel, flat washers and self-locking grower nuts. It is VERY DANGEROUS, not when it is without tension, obviously, but when it exerts force.

Assembly requires no more care than having the correct tools. A system with a tourniquet or threaded rod could help you, it is a matter of how your ingenuity helps you. That they charge you 250 for that is a real robbery, but a cosmetic surgery or losing all your teeth or an eye or both because a metal piece jumps at high speed I think it's more expensive.

Anyway, that is an extension spring, so being in the position shown in the photo should not be exerting force, it would be enough to unhook it by pulling a couple of inches to perform the task you want, Wear protection, thick leather gloves and tools that are of quality and do not slip. You should have help, if possible from someone with enough physical strength to keep the necessary tension while you remove or move the hook. BEWARE, better safe than sorry. Greetings from Argentina