Welcome to JustAnswer!
I am Pete, and I'll be happy to assist with your question today.
Both pedals are linked together inside the machine, and both pedals should be able to move forwards and backwards in a tandem motion.
If the right side is making a ratcheting noise and will only move forward, then this indicates that there is a fault with the internal mechanism that links both sides.
You will need to remove the cover off the rear of the machine and examine the mechanism - if something has slipped out of place, nudge it back in again and ensure it is secure.
Ah ok, I see!
Does it only happen when someone is standing on the machine?
Or does it happen if you move the pedals by hand when no-one is on the machine as well?
Thanks for your response!
The right pedal mechanism is likely clashing with another part of machine and causing the noise.
Can you remove the cover off the rear of the machine and observe the mechanism's movements to identify which parts are clashing and causing the noise?