If your amplifier is overheating it's likely the loudspeakers are at fault. Measure the resistance of the loudspeakers, they are likely rated 8 ohm, it will be indicated on the speaker label. There will be 2 or 3 drive units, often the tweeter can go short circuit causing excessive load.
Simple check for faulty tweeter without opening cabinet,..just cup your hand over the tweeter cone, you should hear a change in the high frequency response. If not its faulty.
Most Technics amps i've come across only operate the fan at medium/high volume levels (about 1/3 volume & above). At low output it's normal for it not to run. If replacing the fan, you should only use the original Technics part.
However, running the amp without a load, ie. no speakers connected can damage the amplifier as there is nothing to dissipate the power, which instead turns into heat.
Make sure you have minimum 3" of clear ventilation above and around the amplifier.
Cobweb
May 2005