A vintage Sony stereo receiver - amp or switch needs repair.

A vintage Sony stereo receiver, the STR-5800SD. The receiver switches on and all the lights work (tuner has two panel meters, and the tip of the tuning indicator turns on for a stereo signal). The preamp and tuner appear to be working fine, and there are 2 tape loops! However, there is no output from the speaker terminals. The speaker selector switch is very loose, so that may be the problem, but it could also be something else. You could use it with one of the small Class-D amplifiers for $50-100 on Amazon (just wire the preamp outputs to the external amplifier and then the speakers). Those little ClassD amps are so small you can tuck it behind the Sony Receiver for the vintage look at a bargain price! There is one button missing, and the tip of the treble control. The metal and the rest of the case are in good condition. It probably weighs about 50lbs, so it is quite a behemoth! I also have vintage, fully working, Altec Lansing speakers from the 1970s, Bose speakers from the 1980s, and an integrated amp (Teac) from the 1980s listed in other ads. The price reflects the fact that it either needs repair or to be used with an external amplifier.