EKO T221: Decreasing sound volume
A case of gradually failing sound volume was investigated and found to be due to the tuning slugs in the coils of the sound channel having shifted. Presumably they had loosened and vibration from the speaker had caused the sound i.f. channel to go gradually off-tune.
Normally this would not be worth reporting but the same fault has been found in more than one receiver, and it affects only the sound channel tuning, the vision response apparently unaffected. It takes some time for the fault to become noticeable, because the user adjusts the volume control to correct it until the extent of the mistuning goes outside the range of the volume control.