You can call them, they may send you to a dealer. Most likely you can just add an actuator, but it is possible that the hub in the chair may not have the extra connector, and you would need another hub to. I doubt that is the case. Hope it goes well, please let us know how it turns out!
Hello, picked up a set of Quest D-box 2 axis chairs and after reading this thread it seems 3 axis is the way to go.
As I picked these up used, who do I contact to see about changing these to 3 axis? Do I call D-box directly?
You would need to add 2 actuators to them given that you said chairs so it sounds like a twin seat/loveseat type configuration, which would have actuators in the rear corners and a ball joint in the front. Each APM can handle a maximum of three actuators so you would need a second APM to install along with another set of actuators and the existing one would need to be reset as a 3 axis system. There were some 2 axis systems sold in the very beginning that are not compatible with the current actuators but those are quite rare - generally the first 2 axis systems made.
3-axis systems are substantially better than the 2 axis systems, I feel. If you have a local dealer, they may be able to help you out, as it will take a field install to get them put in. I don't know if you have a dealer who is capable of doing a field install near you though.