Samba Fans Maraca Problems

I recently bought a used pair of Naki brand maracas (It says King of Maracas on the front) and I'm having some problems with them. One of the maracas work fine, but the other doesn't seem to be able to detect what level it's being held at. It always stays on the top right circle. Does anyone know what could be wrong with these? I've owned Samba de Amigo for 1-2 years and just now I tracked down a set of maracas. Someone please help! T_T

try to swap the maracases to check if the problem comes from the maracas or the ground sensor (don't know if you can, cha cha maracases are plugged to a ground module).
Open the faulty part and check the solders, they may be very bad and need to be removed and replaced by fresh solders.