Distortion of the sound low notes has occurred.
I have changed V14 (EF80), V15 (EF80), V16
(ECL80) and have renewed C85 (112mF) and C87
(200,4F). I have also substituted a good known
loudspeaker.-J. Somers (Portsmouth). A frequent cause of the symptoms you describe
is instability of the last sound i.f. stage, due to a
faulty screen grid decoupling capacitor. Check also
the bias decoupling electrolytic on the sound output valve.