Welcome to the forum.
The Goodmans 110 was a reasonable effort at producing a modern looking receiver. I owned one for a while and was pleased with its performance.
It has appeared before on the forum where part way down are links to the manuals.
https://www.vintage-radio.net/forum/...ad.php?t=46056
Standard repair techniques should work, although it is mainly one large circuit board it is in sections. Check power supplies are present and see if you can hear anything at the tape outputs from the tuner or can produce any sound from the inputs. Don't rule out badly corroded switches and din plugs needing a good clean.
Good Luck