Different channel volumes

As I already wrote, this is my second amplifier with such a problem, but the first one had the loss of the left channel while listening at low volume. On the second amplifier, when turned on first, the left or right channel was quieter. I changed the acoustics, but it didn’t help. I’m currently using tannoy revolution xt6f. I think the relay was stored in a damp environment, made in Thailand. The relay cover can be removed very easily by pressing right and left. So far the problem has not returned. It seemed to me that the sound somehow improved. I cleaned it with a thin pencil eraser, and then ran a strip of paper with pure alcohol along the edges twice. Panasonic ala2pf24 relay, sold here for $8, used in gas boilers…