Distorted audio out of Yamaha-cr-400

Hi, I am having problems with a yamaha cr-400. I am getting distorted audio out of all spk connections. The headphone jack sounds great. I have checked my dc offset and I adjusted it to 5mV. I have cleaned all the pots and switches with cleaner. any help on this would be great!! I can post pictures of anything you may want to see.

Here is the link for the service manual. https://www.dropbox.com/s/8l0vnv0303dyrnv/hfe_yamaha_cr-400_service.pdf?dl=0

Thanks for your time!

The service manual link does not load and does not open.
I found a review on the internet and it looks to be very old with an output of only 16W per channel into 8 ohms.

The headphone socket is just tapped off the speaker outputs, so if the headphones aren't distorted the speaker outputs can't be either.

Have you tried a different pair of speakers?.

As AG says, it's a low power antique though

Assuming the speakers are a similar age?, and if they have foam surrounds? - it's pretty well certain the foam has rotted away.