Hello, my name is XXXXX XXXXX I will try help you with this.
The original rubber buttons were easier to press but do have the problem of wearing out over time. This is why some companies have produced replacements from plastic to be more durable and last longer. However the force needed to use these is different from the force needed to operate the original type.
If you do not like the feel of the new type then all you can do is buy original equipment type replacements that do have the rubber buttons.
These might be more expensive than the ones you have bought from ebay but if it is feel that is bothering you then that is your next option.
If the ones you have bought from ebay don't work at all regardless of how hard you press the button then these are obviously faulty and should be returned for replacement or credit.