Weird thing on my Sansui B-77 Amp

[darren.greer3]

I recently bought this amp, and on certain songs I get one track that won't play. For example on The Beatles Sergeant Pepper I get all the instruments sounding fine on the title track and very low lead guitar and vocal. Same thing on Give Me Your Money on Abbey Road. The only other song I've noticed it on is the sax on Coltrane's My Favourite Things. It does this from my turntable or from the same songs on Itunes. Anyone got any ideas?

 

[jsmithepa]

Bass-Mid-Treble adjust out of wack?

 

[darren.greer3]

Bass-Mid-Treble adjust out of wack?

I tried adjusting and it didn't affect the issue at all. It's like everything in a particular track is muted, and only shows up when the music is recorded in a particular frequency/track. 99.9% of everything is fine, except for the two Beatles and Coltrane. It seems surpassingly strange.

 

[jsmithepa]

Run a pink noise RTA on it.

 

[darren.greer3]

K. First time I've ever done that, but it had a fairly flat response. Adjusted the base and treble and everything moved up and down like it was supposed to, I'm assuming. No major gaps.