How To Fix My Spinning Bike How Can I Fix My Gold's Gym Power Spin 210u Exercise Bike?

How can I fix my Gold's Gym Power Spin 210u exercise bike? - how to fix my spinning bike

Our Spin Turn on the system "ultra-soft" magnetic resistance has suddenly started knocking sounds very strong when we gather at. The sound comes and goes, but it is so strong that others in the room can not hear the TV when someone has a bike. Someone knows what could be the problem?