It does not really matter whether you used them a lot or not. They are 10-11 years old, and there are no more parts available.
This is a domestic group, and you probably have the CIAR motor (if the motor is a problem). You can try googling it and see if someone can sell it to you, but I doubt you would find it. If it is a power supply you may be lucky. I still have some power supplies that Berkline used on their imported groups, and I believe that would work on your chairs as well. The switches are gone, they were discontinued, and were replaced with different ones.
Do check the wiring first and see if none of the wires got caught in the reclining mech and got cut. If not, try to connect the "bad" chair motor to a working chair power supply and see if it can recline. If it can, the power supply/transformer would need to be replaced. If not, you can also check the switch, but switches fail very rarely...
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